以下关于全球气候变暖原因的说法，正确的有：

①世界森林面积不断减小 

②二十世纪以来，太阳辐射逐渐增强 

③地球水域减小显著     

④大量使用矿物燃料

A．①④

B．①②

C．②④

D．③④

She had golden hair when she was a child, but_________ she got older and older; her hair went darker and darker.

A．while

B．when

C．after

D．as