下表是对某生态系统营养级和能量流动情况的调查结果，表中甲、乙、丙、丁分别代表不同

用所给词的适当形式填空。

1. Look at the __________________. How big they are! (library)

2. Look! The boy is __________________ to the classroom. (run)

3. There aren't __________________ exercises on the paper. (some)

4. Children in __________________ often play ping pong. (Chinese)

5. __________________ homework can you do today? (how many)

6. There are some small __________________ near Tianjin. (city)

7. Do you know __________________? (where is he from)

8. Oh, your shoes are like __________________. (Tom)

9. Can you __________________ a horse like that man? (ride)

10. I want to buy two bags of __________________ for the children. (soap)

在半径为1的圆中，180°的圆心角所对的弧长等于（    ）。

轨道车走合保养期间应降低所牵引的平车载重量（）。

神经梅毒首选治疗药物是（）

A.青霉素G

B.头孢曲松钠

C.多西环素

D.头孢噻肟

E.氯霉素

ISDN实现了哪些方面的综合？