从每题所给的ABCD 四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。

　　例：It’s so nice to hear from her again. , we last met more than thirty years ago.

　　A. What’s more B. That’s to say

　　C. In other words D. Believe it or not

　　答案是D。

　　21. Some animals carry seeds from one place to another, ______ plants can spread to new places.

　　A. so B. or

　　C. for D. but

　　22. ---Hi, let’s go skating.

　　--- Sorry, I’m busy right now. I _______ in an application form for a new job.

　　A. fill B. have filled

　　C. am filling D. will fill

　　23. Jane is in a hurry because the train to the airport leaves _______ half an hour.

　　A. by B. in

　　C. for D. until

　　24. ________carefully if any change occurs when doing experiments in the lab..

　　A. Observe B. To observe

　　C. Observed D. Observing

　　25. Last night, there were millions of people _______ the opening ceremony live on TV.

　　A.watch B. to watch

　　C. watched D. watching