()1. What are you doing?
()2. How are you?
()3. Does he learn English?
()4. How many people are there in your class?
()5. Who are they?

【解析】：本题主要考查了日常交际用语以及特殊疑问句的回答。
1. “What are you doing?”是一个现在进行时的特殊疑问句，询问对方正在做什么，根据选项D“I am watching TV.”（我正在看电视。）可知，这是对该问题的合适回答。
2. “How are you?”是一个常见的问候语，询问对方的身体状况或心情，根据选项A“I am fine,thank you.”（我很好，谢谢。）可知，这是对该问候语的常规回答。
3. “Does he learn English?”是一个一般现在时的一般疑问句，询问他是否学习英语，根据选项B“No,he doesn't.”（不，他不学。）可知，这是对该问题的否定回答。
4. “How many people are there in your class?”是一个询问数量的特殊疑问句，根据选项E“There are fifty.”（有五十个。）可知，这是对该问题的合适回答。
5. “Who are they?”是一个询问身份的特殊疑问句，根据选项C“They are my grandparents.”（他们是我的祖父母。）可知，这是对该问题的合适回答。
【答案】：1. D；2. A；3. B；4. E；5. C

1. Is your birthday March?
2. We usually up at 6:30.
3. Which season you like best?
4. Now we in a big house.
5. She sports every day.

1. in
2. get
3. do
4. live
5. plays

1. Sam ate hamburgers today.
2. Sam likes very much.
3. Lingling doesn't like .
4. We gave our hamburgers to .
5. Mum is going to cook Chinese food for .

1. six
2. hamburgers
3. hamburgers
4. Sam
5. Lingling