在中考英语语法专题中，我们将详细解析情态动词和系动词的用法。情态动词表达说话人的态度、能力和可能性，而系动词则用于连接主语和表语，说明主语的状态或特征。

一、情态动词

1. can表示能力或可能性，并在疑问句和否定句中使用，也可以表示许可。例如：

- The parrot can speak three languages.

- Can I borrow the book from the library?

- Shanghai can be very cold in March.

2. may用于表示许可，相当于can，否定回答常用can't/mustn't。may也可用于表示祝愿或推测。例如：

- May I borrow your ruler?

- She may be a teacher.

3. must表示必然性或必要性，疑问句中肯定回答用must，否定回答用needn't或don't have to。must also表示肯定推测，否定形式为mustn't，表示禁止。例如：

- Must I leave now?

- This book must be Lucy's.

- You mustn't draw on the wall.

4. need作为情态动词时，主要用于疑问句和否定句，表示需要。例如：

- Need we finish the work now?

- They needn't look after him.

5. shall用于第一人称，表示征求对方意见，过去式为should。will用于第二人称的疑问句中，表示请求和建议，过去式为would。例如：

- Shall I go shopping with you?

- Would you please come a little earlier?

6. had better用于提出建议，后接动词原形，表示“最好”。例如：

- You'd better ask that policeman over there.

二、系动词

系动词用于连接主语和表语，说明主语的状态或特征。它分为完全系动词和不完全系动词。

1. 完全系动词(be)可以接名词、代词、形容词、副词、介词短语、非谓语动词短语或句子做表语。例如：

- I'm a student.

- He is fine.

- It is me.

- Are you there?

- She is at school.

- He is to come soon.

- My job is teaching English.

- My idea is that we will start now.

2. 不完全系动词(get, turn, feel, smell, look, sound, taste)一般只接形容词做表语。例如：

- When spring comes, it gets warmer and warmer.

- Food may go bad soon if it is not put into a fridge.

- My brother became/turned a teacher after his graduation.