EWL B1 1.2|Grammar - Present Tenses 1|双语课程笔记
EWL B1 1.2|Grammar - Present Tenses 1
Section titled “EWL B1 1.2|Grammar - Present Tenses 1”1. Lesson Goals|本课目标
Section titled “1. Lesson Goals|本课目标”完成本课后,我应该能够:
- 说出 Present Simple 的基本结构
- 正确处理第三人称单数
he / she / it - 正确构造 Present Simple 的肯定句、否定句和一般疑问句
- 说出
be在 Present Simple 中的形式:am / is / are - 说出 Present Continuous 的结构:
be + verb-ing - 正确构造 Present Continuous 的肯定句、否定句和一般疑问句
- 区分“常态”与“正在/暂时发生”
- 在 Speaking 中主动使用两种时态,而不是只会做选择题
2. Bilingual Lesson Transcript|课程双语稿
Section titled “2. Bilingual Lesson Transcript|课程双语稿”2.1 Introduction|引入
Section titled “2.1 Introduction|引入”English
What we’re going to look at today is the present simple and the present continuous. These are two very important present tenses in English.
中文
今天我们要学习的是一般现在时和现在进行时。这是英语中两个非常重要的现在时态。
English
We use the present simple and the present continuous in different situations, so it is important to understand both their forms and their uses.
中文
一般现在时和现在进行时用于不同的情境,因此不仅要理解它们的结构,还要理解它们各自的使用场景。
2.2 Present Simple|一般现在时
Section titled “2.2 Present Simple|一般现在时”A. Basic Form|基本结构
Section titled “A. Basic Form|基本结构”English
Let’s start with the present simple. With most verbs, we use the base form of the verb with I, you, we and they.
中文
先看一般现在时。对于大多数动词,当主语是 I、you、we 和 they 时,我们使用动词原形。
Examples
- I work.
- You work.
- We work.
- They work.
中文
- 我工作。
- 你工作。
- 我们工作。
- 他们工作。
English
With the third person singular — he, she and it — we normally add -s to the verb.
中文
当主语是第三人称单数 he、she、it 时,通常要在动词后面加 -s。
Examples
- He works.
- She walks.
- It looks good.
中文
- 他工作。
- 她走路。
- 它看起来不错。
B. The Verb be|be 动词
Section titled “B. The Verb be|be 动词”English
The verb be is different. In the present simple, it has three forms: am, is and are.
中文
be 动词比较特殊。在一般现在时中,它有三个形式:am、is 和 are。
| Subject | be |
Example |
|---|---|---|
| I | am | I am happy. |
| You | are | You are happy. |
| He | is | He is happy. |
| She | is | She is happy. |
| It | is | It is ready. |
| We | are | We are happy. |
| They | are | They are happy. |
English
We use am with I, is with he, she and it, and are with you, we and they.
中文
I 搭配 am;he / she / it 搭配 is;you / we / they 搭配 are。
2.3 Present Simple Negative|一般现在时否定句
Section titled “2.3 Present Simple Negative|一般现在时否定句”A. Negative with be
Section titled “A. Negative with be”English
In negative sentences with the verb be, we put not after the be verb.
中文
使用 be 动词构成否定句时,直接把 not 放在 be 动词之后。
Examples
- I am not tired.
- He is not tired.
- They are not tired.
中文
- 我不累。
- 他不累。
- 他们不累。
English
In spoken English, we often use contractions such as isn't and aren't.
中文
在口语中,我们经常使用缩写形式,例如 isn't 和 aren't。
- He isn’t tired.
- They aren’t tired.
B. Negative with Other Verbs
Section titled “B. Negative with Other Verbs”English
With other verbs, we use do not or does not plus the base form of the main verb.
中文
其他普通动词构成否定句时,需要使用:
do not / does not + 动词原形
English
We use do not with I, you, we and they.
中文
I / you / we / they 使用 do not。
- I do not work on Sundays.
- They do not live here.
English
We use does not with he, she and it.
中文
he / she / it 使用 does not。
- He does not work on Sundays.
- She does not live here.
English
In everyday spoken English, do not usually becomes don't, and does not usually becomes doesn't.
中文
在日常口语中:
do not → don'tdoes not → doesn't
2.4 Present Simple Questions|一般现在时一般疑问句
Section titled “2.4 Present Simple Questions|一般现在时一般疑问句”A. Questions with be
Section titled “A. Questions with be”English
To make a yes-or-no question with be, we put the be verb before the subject.
中文
使用 be 动词构成一般疑问句时,把 be 动词放到主语前面。
| Statement | Question |
|---|---|
| You are happy. | Are you happy? |
| He is ready. | Is he ready? |
| They are at home. | Are they at home? |
B. Questions with Other Verbs
Section titled “B. Questions with Other Verbs”English
With other verbs, we use do or does before the subject.
中文
普通动词构成一般疑问句时,需要把 do 或 does 放在主语前。
Structure
Do / Does + subject + base verb ... ?
Examples
- Do you work here?
- Do they live in London?
- Does he work here?
- Does she live in London?
中文
- 你在这里工作吗?
- 他们住在伦敦吗?
- 他在这里工作吗?
- 她住在伦敦吗?
does 已经承担了第三人称单数的语法变化,因此主要动词不再加 -s。
2.5 When Do We Use the Present Simple?|一般现在时什么时候用?
Section titled “2.5 When Do We Use the Present Simple?|一般现在时什么时候用?”Use 1|Habits and Routines
Section titled “Use 1|Habits and Routines”English
We use the present simple to talk about habits and routines — things that happen regularly.
中文
一般现在时用于描述习惯和日常规律,也就是经常、重复发生的事情。
Examples
- I get up at seven every day.
- She goes to the gym three times a week.
- We usually have dinner at home.
中文
- 我每天七点起床。
- 她每周去三次健身房。
- 我们通常在家吃晚饭。
Use 2|Facts and General Truths
Section titled “Use 2|Facts and General Truths”English
We also use the present simple for facts and things that are generally true.
中文
一般现在时也用于描述事实以及通常成立的情况。
Examples
- Water boils at 100 degrees Celsius.
- The Earth goes around the Sun.
- London is in the United Kingdom.
中文
- 水在 100 摄氏度时沸腾。
- 地球围绕太阳运行。
- 伦敦位于英国。
Use 3|Permanent or Relatively Stable Situations
Section titled “Use 3|Permanent or Relatively Stable Situations”English
We use the present simple for situations that we see as permanent or relatively stable.
中文
当我们认为一个状态是长期、稳定或相对固定的时候,也使用一般现在时。
Example
- James lives in Manchester.
中文
James 住在曼彻斯特。
这里的意思通常是:说话者认为这是 James 比较稳定的居住状态。
Use 4|Schedules and Timetables
Section titled “Use 4|Schedules and Timetables”English
The present simple can also be used for scheduled events, such as train times, flight times and timetables.
中文
一般现在时还可以描述已经按照时间表确定的事件,例如火车、航班、课程等。
Examples
- The train leaves at eight.
- The lesson starts at nine.
- My flight departs tomorrow morning.
中文
- 火车八点出发。
- 课程九点开始。
- 我的航班明天早上起飞。
2.6 Present Continuous|现在进行时
Section titled “2.6 Present Continuous|现在进行时”A. Structure|结构
Section titled “A. Structure|结构”English
Now let’s look at the present continuous. We form it with the verb be and the -ing form of the main verb.
中文
接下来学习现在进行时。它由:
be + 动词-ing
构成。
Structure
Subject + am / is / are + verb-ing
Examples
- I am working.
- You are working.
- He is working.
- She is working.
- We are working.
- They are working.
中文
这些句子都表示“正在工作”。
English
Remember that the form of be changes depending on the subject.
中文
注意:be 动词要根据主语进行变化。
- I am
- he / she / it is
- you / we / they are
2.7 Present Continuous Negative|现在进行时否定句
Section titled “2.7 Present Continuous Negative|现在进行时否定句”English
To make a negative sentence, we put not after the verb be.
中文
现在进行时的否定句是在 be 动词后面加 not。
Structure
Subject + be + not + verb-ing
Examples
- I am not working.
- He is not working.
- They are not working.
中文
- 我现在没有在工作。
- 他现在没有在工作。
- 他们现在没有在工作。
Common contractions
- isn’t = is not
- aren’t = are not
Examples
- She isn’t sleeping.
- We aren’t waiting.
2.8 Present Continuous Questions|现在进行时一般疑问句
Section titled “2.8 Present Continuous Questions|现在进行时一般疑问句”English
To make a yes-or-no question, we move the verb be before the subject.
中文
构成现在进行时的一般疑问句时,把 be 动词移到主语之前。
Structure
Am / Is / Are + subject + verb-ing ... ?
Examples
- Are you working?
- Is he sleeping?
- Are they waiting?
中文
- 你正在工作吗?
- 他正在睡觉吗?
- 他们正在等吗?
2.9 When Do We Use the Present Continuous?|现在进行时什么时候用?
Section titled “2.9 When Do We Use the Present Continuous?|现在进行时什么时候用?”Use 1|Actions Happening Now
Section titled “Use 1|Actions Happening Now”English
We use the present continuous for actions that are happening now, at or around the moment of speaking.
中文
现在进行时用于描述说话这一刻正在发生,或围绕当前时间正在进行的动作。
Examples
- I am speaking English.
- You are listening to this lesson.
- She is talking on the phone.
中文
- 我正在说英语。
- 你正在听这节课。
- 她正在打电话。
Use 2|Temporary Situations
Section titled “Use 2|Temporary Situations”English
We can also use the present continuous for situations that we think are temporary.
中文
现在进行时还可以表示我们认为是暂时性的情况。
Compare
- James lives in Manchester.
- James is living in Manchester.
中文
-
James lives in Manchester.
→ 我认为他长期/稳定地住在那里。 -
James is living in Manchester.
→ 他目前住在那里,但这个状态可能只是暂时的。
English
The grammar we choose tells the listener how we see the situation.
中文
这里真正重要的是:
我们选择什么时态,会告诉听者我们如何看待这个状态。
不是只看“现在”两个字,而要判断:
- 它是常态吗?
- 它是长期的吗?
- 还是当前阶段暂时发生的?
2.10 Present Simple vs Present Continuous|核心对比
Section titled “2.10 Present Simple vs Present Continuous|核心对比”English
Compare these two ideas:
I work from home.
I am working from home today.
中文
比较:
I work from home.
我平时在家办公。→ 常态 / 工作习惯
I am working from home today.
我今天正在家办公。→ 今天暂时如此
English
Another example:
She usually drives to work.
She is taking the bus today.
中文
再看:
She usually drives to work.
她通常开车上班。
She is taking the bus today.
她今天坐公交车上班。
2.11 Lesson Summary|课程结尾总结
Section titled “2.11 Lesson Summary|课程结尾总结”English
So remember: use the present simple for habits, routines, facts and situations that you see as permanent. Use the present continuous for actions happening now and for situations that you see as temporary.
中文
总结:
一般现在时用于:
- 习惯
- 日常规律
- 事实
- 长期或稳定状态
现在进行时用于:
- 正在发生的动作
- 当前阶段发生的事情
- 暂时性的情况
English
Pay particular attention to the third person singular in the present simple, and remember that after does or doesn't, we use the base form of the verb.
中文
尤其要注意一般现在时的第三人称单数。
并记住:
does / doesn't后面的主要动词一定使用原形。
English
With the present continuous, remember the complete structure: be + verb-ing. Do not forget the verb be.
中文
使用现在进行时时,必须记住完整结构:
be + verb-ing
不要漏掉 be 动词。
3. Core Grammar Notes|课程重点笔记
Section titled “3. Core Grammar Notes|课程重点笔记”3.1 一般现在时结构
Section titled “3.1 一般现在时结构”| Subject | Structure | Example |
|---|---|---|
| I / You / We / They | base verb | I work here. |
| He / She / It | verb + s/es |
She works here. |
be |
am / is / are | He is busy. |
| 类型 | Structure | Example |
|---|---|---|
| 普通动词 | do/does + not + base verb | She doesn’t work here. |
be |
am/is/are + not | She isn’t busy. |
| 类型 | Structure | Example |
|---|---|---|
| 普通动词 | Do/Does + subject + base verb? | Does she work here? |
be |
Am/Is/Are + subject…? | Is she busy? |
3.2 现在进行时结构
Section titled “3.2 现在进行时结构”Subject + am/is/are + verb-ing
She is working.
Subject + am/is/are + not + verb-ing
She isn’t working.
Am/Is/Are + subject + verb-ing?
Is she working?
3.3 一般现在时 vs 现在进行时
Section titled “3.3 一般现在时 vs 现在进行时”| 判断维度 | Present Simple | Present Continuous |
|---|---|---|
| 核心概念 | 常态 | 当前过程 |
| 习惯 | ✅ | — |
| 日常规律 | ✅ | — |
| 客观事实 | ✅ | — |
| 稳定状态 | ✅ | — |
| 正在发生 | — | ✅ |
| 当前阶段 | — | ✅ |
| 暂时状态 | — | ✅ |
| 结构 | base verb / s |
be + ing |
| 示例 | I work from home. | I am working from home today. |
4. Must-Master Error List|必须消灭的错误
Section titled “4. Must-Master Error List|必须消灭的错误”Error 1|第三人称单数漏 -s
Section titled “Error 1|第三人称单数漏 -s”❌ He work here.
✅ He works here.
Error 2|doesn't 后继续加 -s
Section titled “Error 2|doesn't 后继续加 -s”❌ She doesn’t likes coffee.
✅ She doesn’t like coffee.
Error 3|does 疑问句后继续加 -s
Section titled “Error 3|does 疑问句后继续加 -s”❌ Does he works here?
✅ Does he work here?
Error 4|现在进行时漏掉 be
Section titled “Error 4|现在进行时漏掉 be”❌ I working now.
✅ I am working now.
Error 5|把常态错误地用成进行时
Section titled “Error 5|把常态错误地用成进行时”❌ I am going to work every day.
✅ I go to work every day.
注意:
I am going to...还可能构成未来表达,因此必须根据完整语境判断。
Error 6|把正在发生的事情误用一般现在时
Section titled “Error 6|把正在发生的事情误用一般现在时”❌ I eat dinner right now.
✅ I am eating dinner right now.
5. Active Vocabulary & Chunks|主动词汇与句块
Section titled “5. Active Vocabulary & Chunks|主动词汇与句块”本课语法课的重点不是大量背单词,因此只保留高价值 Teacher English / Grammar Chunks。
| Chunk | 中文 | 用法 |
|---|---|---|
What we're going to look at today is... |
今天我们要学习的是…… | Teacher English |
the present simple |
一般现在时 | Grammar |
the present continuous |
现在进行时 | Grammar |
the base form of the verb |
动词原形 | Grammar |
third person singular |
第三人称单数 | Grammar |
negative sentence |
否定句 | Grammar |
yes-or-no question |
一般疑问句 | Grammar |
a habit or routine |
习惯或日常规律 | 高频语义 |
at the moment |
此刻;目前 | Continuous 信号 |
a temporary situation |
暂时情况 | Continuous 核心语义 |
a permanent situation |
长期/稳定情况 | Simple 核心语义 |
depending on the subject |
取决于主语 | Teacher English |
6. Listening Focus|精听重点
Section titled “6. Listening Focus|精听重点”Sentence 1
Section titled “Sentence 1”What we’re going to look at today is the present simple.
中文:今天我们要学习的是一般现在时。
What we're going to look at today
→ 我们今天要学习的内容
is the present simple
→ 是一般现在时
Sound Focus
Section titled “Sound Focus”we're=we aregoing to在自然语流中通常弱化look at容易发生连读- 句子重音通常落在
look,today,present simple
Sentence 2
Section titled “Sentence 2”With the third person singular, we normally add -s to the verb.
中文:第三人称单数时,我们通常在动词后加 -s。
Listening Trap
Section titled “Listening Trap”third person singular 是一个完整语法词块,不要逐词翻译后再理解。
Sentence 3
Section titled “Sentence 3”In negative sentences, the be verb is followed by not.
中文:在否定句中,be 动词后面接 not。
be followed by
→ 后面跟着……
Sentence 4
Section titled “Sentence 4”We use do not or does not with the base form of the verb.
中文:我们使用 do not 或 does not 加动词原形。
Sentence 5
Section titled “Sentence 5”After does or doesn't, we use the base form of the verb.
中文:在 does 或 doesn't 之后,我们使用动词原形。
Sentence 6
Section titled “Sentence 6”The present continuous is formed with be and the -ing form of the verb.
中文:现在进行时由 be 加动词的 -ing 形式构成。
Sentence 7
Section titled “Sentence 7”We use the present continuous for actions that are happening now.
中文:我们使用现在进行时描述正在发生的动作。
Sentence 8
Section titled “Sentence 8”We can also use it for situations that we think are temporary.
中文:我们也可以用它描述我们认为是暂时性的情况。
7. Personal Sentence Bank|我的个人句子库
Section titled “7. Personal Sentence Bank|我的个人句子库”不要写与自己无关的 Tom goes to school。
请完成下面至少 5 句:
- I usually __________________________________________.
- I don’t usually ____________________________________.
- I am ________________________________________ right now.
- This week, I am ____________________________________.
- I normally __________________________________, but today I am __________________________________.
- My company _________________________________________.
- One of my colleagues _________________________________________.
8. Mastery Test|课后测试
Section titled “8. Mastery Test|课后测试”Part A|Grammar Recognition
Section titled “Part A|Grammar Recognition”She ______ to work at 9 every morning.
A. go
B. goes
C. is going
- 我的答案:
Look! She ______ to the manager now.
A. talks
B. is talking
C. talk
- 我的答案:
He ______ coffee.
A. doesn’t likes
B. doesn’t like
C. isn’t like
- 我的答案:
______ your brother work in London?
A. Do
B. Does
C. Is
- 我的答案:
They ______ from home this week.
A. work
B. works
C. are working
- 我的答案:
9. Sentence Transformation|句型转换
Section titled “9. Sentence Transformation|句型转换”将下面句子改成否定句:
She works here.
- ________________________________________
改成一般疑问句:
He lives in London.
- ________________________________________
改成否定句:
They are working.
- ________________________________________
改成一般疑问句:
She is studying English.
- ________________________________________
10. Tense Choice|时态选择
Section titled “10. Tense Choice|时态选择”我平时每天早上 8 点开始工作。
- ________________________________________
我现在正在学习英语。
- ________________________________________
我通常在办公室工作,但是这周我在家办公。
- ________________________________________
11. Error Correction|纠错
Section titled “11. Error Correction|纠错”找出并改正错误。
He don’t work here.
- ________________________________________
Does she works in marketing?
- ________________________________________
I studying English now.
- ________________________________________
She is go to the gym every Monday.
- ________________________________________
They doesn’t live here.
- ________________________________________
12. Speaking Mission|口语任务
Section titled “12. Speaking Mission|口语任务”Level 1|Controlled
Section titled “Level 1|Controlled”回答:
What do you usually do after work?
要求:
-
Present Simple
-
至少 3 句
-
使用
usually / often / sometimes中至少一个 -
已完成
Level 2|Guided
Section titled “Level 2|Guided”回答:
What are you working on or learning at the moment?
要求:
-
Present Continuous
-
至少 4 句
-
使用
at the moment / currently / this week中至少一个 -
已完成
Level 3|Free Speaking
Section titled “Level 3|Free Speaking”My normal routine vs what I am doing these days
说 1–2 分钟。
必须至少出现:
-
3 × Present Simple
-
3 × Present Continuous
-
1 ×
usually -
1 ×
at the moment -
1 ×
but -
已完成
13. Listening Mastery Check|听力掌握测试
Section titled “13. Listening Mastery Check|听力掌握测试”重新播放原音频,不看字幕。
Round 1|Main Idea
Section titled “Round 1|Main Idea”- 我能判断这一段在讲 Present Simple 还是 Present Continuous
- 不要求逐字听懂
Round 2|Grammar Words
Section titled “Round 2|Grammar Words”检查我能否直接听出:
- present simple
- present continuous
- third person singular
- base form
- negative sentence
- question
- temporary
- subject
- verb
Round 3|Core Sentences
Section titled “Round 3|Core Sentences”- 我能听懂至少 6/8 个核心句
- 我没有先翻译中文再理解
- 我能 Shadow 至少 5 个句子
14. Pronunciation Check|发音检查
Section titled “14. Pronunciation Check|发音检查”-
present在present simple中能自然读出 -
continuous重音位置基本正确 -
third person singular能作为词块连贯说出 -
doesn't/ˈdʌzənt/ 不逐字母发音 -
going to能识别自然弱读 -
look at能识别连读 -
we're能直接识别为we are
15. Active Recall|不看笔记回答
Section titled “15. Active Recall|不看笔记回答”请口头回答:
- What is the basic structure of the present simple?
- What happens with
he,sheandit? - How do we make a negative sentence with
be? - How do we make a negative sentence with a normal verb?
- What happens to the main verb after
doesn't? - How do we form the present continuous?
- When do we use the present simple?
- When do we use the present continuous?
- What is the difference between:
James lives in Manchester.James is living in Manchester.
- Give one example from your own life for each tense.
16. Mastery Scorecard|掌握度评分
Section titled “16. Mastery Scorecard|掌握度评分”| Dimension | Score | Pass Standard |
|---|---|---|
| Grammar | /20 | ≥16 |
| Active Vocabulary | /20 | ≥16 |
| Listening | /20 | ≥16 |
| Speaking | /20 | ≥16 |
| Pronunciation | /20 | ≥16 |
| Total | /100 | ≥80 |
Result
Section titled “Result”- A|90–100|Mastered
- B|80–89|Mostly Mastered
- C|70–79|Unstable
- D|<70|Review Required
17. Answer Key|答案
Section titled “17. Answer Key|答案”点击展开答案
Part A
Section titled “Part A”- B — goes
- B — is talking
- B — doesn’t like
- B — Does
- C — are working
Sentence Transformation
Section titled “Sentence Transformation”-
She doesn’t work here.
-
Does he live in London?
-
They aren’t working.
或:They are not working. -
Is she studying English?
Translation
Section titled “Translation”-
I start work at eight every morning.
-
I am studying English now.
-
I usually work in the office, but I am working from home this week.
Error Correction
Section titled “Error Correction”-
❌ He don’t work here.
✅ He doesn’t work here. -
❌ Does she works in marketing?
✅ Does she work in marketing? -
❌ I studying English now.
✅ I am studying English now. -
❌ She is go to the gym every Monday.
✅ She goes to the gym every Monday. -
❌ They doesn’t live here.
✅ They don’t live here.
18. Spaced Review|间隔复习
Section titled “18. Spaced Review|间隔复习”Day 0|今天
Section titled “Day 0|今天”- 完成本课音频
- 完成 Grammar Test
- 完成 5 个 Personal Sentences
- Shadow 5–8 个核心句
- 完成 1 分钟 Speaking
Day +1
Section titled “Day +1”- 不看笔记说出两种时态结构
- 重新做 Error Correction
- 听核心句
Day +3
Section titled “Day +3”- 口头造 5 句 Present Simple
- 口头造 5 句 Present Continuous
- 完成 Simple vs Continuous 对比
Day +7
Section titled “Day +7”- 随机 Grammar Test
- 原音频无字幕再听
- 1–2 分钟 Speaking
Day +14
Section titled “Day +14”- Active Recall
- 检查第三人称单数错误是否消失
- 检查是否仍漏
be
Day +30
Section titled “Day +30”- 综合测试
- 若 ≥80%,标记 Mostly Mastered
- 若 ≥90% 且口语可主动调用,标记 Mastered
19. Error Bank Entry|错误库模板
Section titled “19. Error Bank Entry|错误库模板”| ID | Type | Error | Correct Form | Status |
|---|---|---|---|---|
| B1-1.2-G01 | Grammar | He work… | He works… | New |
| B1-1.2-G02 | Grammar | doesn’t works | doesn’t work | New |
| B1-1.2-G03 | Grammar | Does she works? | Does she work? | New |
| B1-1.2-G04 | Grammar | I working… | I am working… | New |
20. Sound Gap Bank|听力断层记录
Section titled “20. Sound Gap Bank|听力断层记录”当出现:
“文字看得懂,但是音频里听不出来。”
记录到这里:
| Sentence / Chunk | 我听成什么 | Actual | Cause | Status |
|---|---|---|---|---|
| What we’re going to look at today… | linking / weak form | New | ||
| third person singular | chunk gap | New | ||
| does not / doesn’t | pronunciation | New | ||
| at the moment | linking | New |
21. 本课最终 80/20
Section titled “21. 本课最终 80/20”如果我一个月后只记得本课 6 件事,必须是:
I/you/we/they + base verbhe/she/it + verb-sdoes/doesn't + base verb- Present Simple = 习惯 / 事实 / 常态
- Present Continuous =
be + verb-ing - Present Continuous = 正在发生 / 暂时状态
Next Lesson Gate
Section titled “Next Lesson Gate”进入下一课前,我应该能够不看答案完成:
I usually ________, but today I am ________.
并解释为什么前半句使用 Present Simple,后半句使用 Present Continuous。