换热器总传系数取决于流体的性质、传热过程的操作条件以及（）。
A.换热器热负荷
B.换热器类型
C.物料进量
D.循环水温度
参考答案：B
—What do you think of the rules?
—I think the sixteen-year-olds should be allowed _____ sports after school. [ ]
A. to play
B. playing
C. played
D. to playing
The girl _________ won the gold medal comes from Beijing Sunshine Secondary School.[ ]
A. who
B. which
C. what
D. whom
