从零学英语Day18,掌握时间表达，轻松驾驭When句型！
Day 18: Using "When" in English
In English, "when" is a subordinating conjunction that is used to introduce adverbial clauses that give information about time. Here are some key points about using "when":
1. "Simple Present for Future Actions": Use the simple present tense to talk about future actions that will happen at a specific time in the future.
- Example: I will go to the movies when the movie starts.
2. "Present Continuous for Ongoing Actions": Use the present continuous tense to talk about actions that are happening at the moment the main action is taking place.
- Example: I will be watching the movie when you arrive.
3. "Simple Past for Past Actions": Use the simple past tense to talk about actions that happened at a specific past time.
- Example: I watched the movie when you called me.
4. "Past Continuous for Ongoing Actions": Use the past continuous tense to talk about actions that were happening at a specific past time.
- Example: I was watching the movie when you called me.
5. "Present Perfect for Actions with Present Relevance": Use the present perfect tense to talk about actions that started in the past and continue to the present, or actions that are related to the present.
- Example: I have watched this movie when I was a child.
6. "Past Perfect for Actions Before Another Past Action": Use the past perfect tense to talk about actions that
相关内容：
你什么时候(何时)教他英文？
When do you teach him English?
When当疑问词：在疑问词的场景下表示“什么时候”的意思， When放在句首，且放在do/does之前形成疑问语气。
He teaches me English. 他教我英语。Does he teach me English? 他教我英语吗？有助动词 does teaches变原型teachWhen does he teach me English? 他什么时候教我英语？ 有助动词 does teaches变原型teach同理 Where/Why/How/What 也是类似使用What does he have? 他有什么 （东西）？Where does he teach me English? 他在哪里教我英语？Why does he teach me English? 他为什么教我英语？How does he teach me English? 他如何教我英语？When当连词： 意思是“当....时候“，用法和“because"一样可连接两个句子。
When放句首“when + 句1 + , + 句2"When she is sick, she is sad.When放句中"句1+when+句2"She is sad when she is sick.总结：
When是一个疑问词，表示“什么时候”，也可以作为副词，表示“在什么时候”。下面分别介绍when的使用方法：
- 作为疑问词，when通常用来询问时间，引导疑问句。例如：
- When is your birthday?（你的生日是什么时候？）
- When will you arrive at the airport?（你什么时候到达机场？）
- 当when用作副词时，它通常修饰表示时间的动词或者介词短语，表示某个动作或者事件发生的时间。例如：
- She arrived at the airport when the plane took off.（当飞机起飞时，她到达了机场。）
- I will call you back when I finish work.（当我下班后，我会给你回电话。）
- 当when作为连词时，它通常引导时间状语从句，表示一个事件发生的时间。例如：
- I was watching TV when my friend came over.（当我朋友来的时候，我正在看电视。）
- He always feels tired when he wakes up early.（当他早起时，他总是感到疲劳。）
需要注意的是，when可以表示的时间范围比较广泛，可以是具体的时间点、时间段、日期等等。在使用时，需要根据具体语境来理解和解释when的含义。
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