根据句意，用括号内所给动词的正确形式填空。

1. They _______ (chat) online when Amy came up the stairs.

2. When I got home, I found my pet dog _______ (lie) on the floor, dead.

3. —I'm sorry I forgot _______ (post) your letter on my way home. 

    —That's OK. I will do it myself this afternoon.

4. She tells her son to have his hair _______ (cut) every other month.

5. Yesterday, she ________ (make) to finish all the work in a short time by his boss.

（）是完全变态昆虫的一个世代中可以没有的虫态。

A、卵

B、幼虫

C、若虫

D、成虫