词形变化。

1. Mr. Smith and his family ______ (be) in the park now.

2. Do you go _______ (fish) at the weekends?

3. There are two ________ (library) in our school.

4. On the _____ (five) floor, there are two toilets.

5. Let _____ (I) have a look.

6. Would you like _______ (go) with me?

7. What _____ she usually ______ (eat) for lunch?

8. (not look) _____ out of the classroom.

9. Who ______(have) a pet in your class?

10. My ball is blue. ______(She) is yellow.

某筛子给矿某粒级含量为55%，筛下含量为95%，筛上含量为5%，该筛子的筛分效率是多少