结构化设计采用模块化方法的主要出发点是（）。
A、增加内聚性
B、减少耦合度
C、提高有效性
D、降低复杂度
参考答案：D
Both his parents look sad. Maybe they _ what's happened to him. [ ]
A. knew
B. had known
C. have known
D. will know
公共建筑应急照明配电箱供电范围不宜超过（）层。
A.8
B.10
C.12
D.16
