During the famine, many people were ______ to going without food for days.

A．sunk

B．reduced

C．forced

D．declined

就整个地球大气来说，能量的根本来源是太阳辐射，太阳辐射能被大气接收和转化的过程十分复杂，其加热大气的过程大致可以用下图表示。读图完成下列小题。

多云的天气昼夜温差较小，主要是因为（）

A.②增强，③减弱

B.②减弱，③增强

C.③增强，④减弱

D.②减弱，④增强