He wrote a lot of novels, ______ regarded as masterpieces.

A．dozens of them

B．dozens of which

C．a dozen of which

D．dozen of that

晴朗的天空呈现蔚蓝色，是由于太阳光穿过大气层时（）

A.直接到达地面的蓝光比重大

B.空气分子使蓝光发生散射作用

C.高层大气分子大量吸收蓝色光

D.到达地面的蓝色光又完全被反射到高空