材料订购费随订购次数的增加而（），在总用量不变的条件下，与订购的批量成（）
A.增加，正比
B.降低，反比
C.增加，反比
D.降低，正比
参考答案：C
用所给词的正确形式填空。
1. The old man dislikes (live) in the city.
2. My plane (take) off at 5 p.m..
3. I wonder if you (buy) a stamp for me.
4. I want to know where he (go) for his holiday.
5. Hurry up, please, the train (leave) in a minute.
6. We (have) rice for lunch today.
7. Where you (spend) Christmas this year?
8. Who (see) you off tomorrow?
9. The train (arrive) in five minutes.
10. Don't worry. Your son (be) all right.
架空线路杆塔保护接地的接地电阻不宜大于( )。
A．30Ω B．20Ω C．10Ω D．4Ω
