水性“润下”的引申义是（）
A.炎热
B.滋润
C.寒凉
D.闭藏
E.下行
参考答案：B, C, D, E
--Did you listen to the report last Friday?
--- Yes, it was about the shortage of migrant workers. That was the first time I______ about the subject.
A．heard
B．was hearing
C．would hear
D．had heard
下列几何体中，不属于多面体的是（ ）
A．正方体
B．三棱柱
C．长方体
D．圆柱
