Those who _____ in ____ compositions, please hand them in this afternoon.

A．hasn't handed; his

B．haven't handed; their

C．has handed; their

D．have handed; his

植物经常萎蔫对生长是有害的，农业生产上常用黏性的塑料覆盖在叶的表面，形成一层透明的薄膜，它能使氧气、二氧化碳和光线透过，水则不能透过．该薄膜的适用情况是（　　）

A．连续降雨时

B．炎热夏季的强光下

C．低温环境中

D．秋末落叶时