—Growing population resulted in growing rubbish.

—There is ______that rubbish will become the major threat to human beings in future.

A．hope

B．afraid

C．possibility

D．likely

农民经常给农作物松土，其主要作用是（　　）

A．促进植物进行蒸腾作用

B．促进植物进行光合作用

C．促进植物根的呼吸作用

D．有利于根的生长