Some students are ______ in the classroom . （   ）

A．sing

B．singing

C．sung

---What are they doing?
---They're the paper.

A．cut

B．cutting

C．cuting

用进行时态用所给词造句：They, eat rice. _______________________________

用所给词的适当形式填空。
【小题1】They _________ (spend) their holiday in London last month.
【小题2】Kitty enjoyed _________ (her) at Tom’s birthday party.
【小题3】Lucy is _________ (write) a postcard now.
【小题4】I am _________ (have) a good time in Guangzhou. I _________ (come) here by plane last week.
【小题5】Joe is good at ____________ (climb) mountains. He wants to climb Mount Tai.

Tom is ___________.（）

A．laugh

B．laughing

C．laughed