从方框中选适当的选项补全对话。

A：Hi, Tom. You look so worried. 小题1:

B：We are going to have a basketball game against Class Two. But Jack fell    ill. He can’t take part in it.

A：I am sorry to hear that.

B：David,   小题2:

A：Sure. What is it?

B：小题3:

A：I’d be glad to. But I’m not good at playing basketball.

B：Never mind. I’m sure you can do it well.

A：I will do my best.  小题4:

B：Of course not.  小题5:

A：OK. Thank you very much. See you later.

B：See you.

发动机运转时，排气管放炮，发动机体振动较大，油耗升高，则可能是（）

A.点火过早

B.点火过晚

C.断火