be类助动词与现在分词连用表达正在进行的动作

be类助动词与现在分词连用表达正在进行的动作
在英语中，be类助动词是构成进行时态的关键成分。它们的主要功能是协助主要动词，表达正在进行的动作或状态。

首先，我们要明确什么是进行时态。进行时态用于描述在某一特定时间或时间段内正在进行的动作或状态。在英语中，进行时态通常通过在动词后添加-ing形式来构成。

be类助动词在构成进行时态时，需要与现在分词（即动词的-ing形式）一起使用。具体来说，be动词（am、is、are用于现在时，was、were用于过去时）与现在分词结合，形成现在进行时和过去进行时。
1. 现在进行时：表示现在正在进行的动作或状态。例如：
- She is studying.（她正在学习。）
- They are playing football.（他们正在踢足球。）
在现在进行时的句子中，be动词的形式（am、is、are）需要根据主语的人称和数来选择。同时，现在分词（动词的-ing形式）用于描述正在进行的动作。
抗遗忘英语单词速记
 随时随地背单词
 不知不觉背单词
 单词不用记

2. 过去进行时：表示过去某一时刻或某段时间内正在进行的动作或状态。例如：
- When I called him, he was having a meeting.（我给他打电话时，他正在开会。）
- They were watching TV when the power went out.（停电时，他们正在看电视。）
在过去进行时的句子中，be动词的形式（was、were）同样需要根据主语的人称和数来选择。现在分词则用于描述过去正在进行的动作。

需要注意的是，进行时态并不适用于所有动词。有些动词，如表示状态、感觉、拥有等意义的动词，通常不使用进行时态。此外，进行时态还可以与always、constantly等副词连用，强调动作的持续性或频繁性。

总结来说，be类助动词在构成进行时态时，需要与现在分词结合使用，表达正在进行的动作或状态。根据时态的不同（现在进行时或过去进行时），be动词的形式也会有所变化。通过掌握这些用法辨析，我们可以更准确地运用英语进行时态来表达复杂的动作和状态。

一、选择题
1. They _______ a movie when the power suddenly went out.
A. were watching B. watched C. are watching D. watch
2. She _______ a letter to her friend when the phone rang.
A. writes B. wrote C. was writing D. is writing
3. Last night, we _______ a party in the garden.
A. had B. were having C. have D. are having
4. At this time tomorrow, I _______ a meeting with my boss.
A. will have B. am having C. will be having D. have
5. When he came in, they _______ a discussion about the project.
A. had B. have been having C. were having D. have

二、填空题
1. She _______ (work) in the garden when I saw her last Sunday.
2. They _______ (play) football on the playground at that time.
3. I _______ (not read) a book at 9 o'clock last night. I _______ (watch) TV.
4. What _______ you _______ (do) when I called you just now?
5. Last year at this time, we _______ (prepare) for the final exam.

三、改错题
1. She is singing a song while she is doing her homework. (改为正确的进行时态)
2. They were play in the park last Sunday. (改为正确的进行时态)
3. He watches TV every evening. (改为现在进行时态)
4. We are having a party last night. (改为正确的时态)
5. They had a discussion about the plan yesterday. (改为过去进行时态)

一、选择题解析
1.【答案】A
【解析】句子描述的是电力突然中断时他们正在做的事情，因此应使用过去进行时态，选项A的“were watching”符合语境。
2.【答案】C
【解析】句子中提到电话响时她正在做的事情，所以应使用过去进行时态，选项C的“was writing”正确。
3.【答案】B
【解析】句子中提到的时间是“昨晚”，但描述的是正在进行的活动，因此应使用过去进行时态，选项B的“were having”符合要求。
4.【答案】C
【解析】句子描述的是将来某个时间点的进行时态，应使用将来进行时态，选项C的“will be having”正确。
5.【答案】C
【解析】句子中提到他进来时他们正在做的事情，所以应使用过去进行时态，选项C的“were having”正确。

二、填空题解析
1.【答案】was working
【解析】根据句子中的“last Sunday”和“when I saw her”，应使用过去进行时态，因此填“was working”。
2.【答案】were playing
【解析】句子中提到的是过去某个时间正在进行的动作，应使用过去进行时态，因此填“were playing”。
3.【答案】wasn't reading; was watching
【解析】句子描述的是过去某个时间点正在进行的动作，应使用过去进行时态。且句子中使用了否定词“not”，所以第一个空应填“wasn't reading”；第二个空描述的是另一个同时进行的动作，填“was watching”。
4.【答案】What were; doing
【解析】句子中使用的是过去时态的“called”，询问的是过去某个时间点的进行时态，应使用过去进行时态，因此填“What were; doing”。
5.【答案】were preparing
【解析】句子中提到的是去年这个时候正在做的事情，应使用过去进行时态，因此填“were preparing”。

三、改错题解析
1.【答案】She is singing a song while she is doing her homework. 改为 She is singing a song while she is doing her homework. (无需改动，句子已经是正确的现在进行时态)
2.【答案】They were play in the park last Sunday. 改为 They were playing in the park last Sunday. (将“play”改为“playing”，构成过去进行时态)
3.【答案】He watches TV every evening. 改为 He is watching TV every evening. (将“watches”改为“is watching”，构成现在进行时态)
4.【答案】We are having a party last night. 改为 We were havinga party last night. (将“are”改为“were”，构成过去进行时态)
5.【答案】They had a discussion about the plan yesterday. 改为 They were having a discussion about the plan yesterday. (将“had”改为“were having”，构成过去进行时态)