当传热面积一定，管子数目一定时，增加管程对传热系数的影响有（）。
A.传热系数降低
B.传热系数增加
C.传热系数不变
D.都不对
参考答案：B
当给料中细粒煤含量超过（）时，最好预先脱泥。
A、20％
B、30％
C、25％
根据句意及首字母的提示，补全单词。
1. Tom's father is a d_____ manager in the company.
2. The store is three b_____ away. You can walk there.
3. You can buy f_____ fruit and vegetables in the market.
4. They b_____ that it was all done by magic.
5. The chair is of solid o_____, so it is very expensive.
