以下是七年级下册英语中常见的句型分类整理，结合了不同单元的核心句型结构：

一、一般疑问句

情态动词 + 主语 + 动词原形

- Can you play the guitar？

- Must I finish my homework today？

特殊疑问词 + 动词原形

- What time do you go to school？

- Where is the nearest post office？

How引导的疑问句

- How do you get to school？

- How long does it take to finish homework？

二、现在进行时

结构：

be动词（am/is/are） + 动词ing形式

I am watching TV right now.

They are playing football in the park.

三、一般过去时

结构：主语 + 动词的过去式

Yesterday, I visited my grandparents.

Last weekend, we watched a movie.

四、现在完成时

结构：主语 + have/has + 过去分词

I have finished my homework already.

She has been studying English for three years.

五、常用表达

频度副词

- always, never, sometimes, often

- I always wake up at 7 AM.

- They never forget to say goodbye.

固定搭配

- can't help but + 动词原形

- I can't help but smile at cute animals.

- must have done

- The homework is done, must have been you.

六、特殊句型

间接引语

Direct: He said, "I love playing football."

Indirect: He said that he loves playing football.

条件句

If + 动词原形， ...

- If it rains, we will cancel the picnic.

If + 动词过去分词， ...

- If finished, we can go out.

以上句型覆盖了七年级下册的主要语法点，建议结合具体语境进行练习和应用。