下列叙述正确的是（　　）

A．饱和溶液降温时，一定有溶质析出

B．饱和溶液不能再溶解任何物质

C．饱和溶液一定比不饱和溶液浓

D．一定温度下，饱和溶液中的溶质和溶剂的质量比是个定值

You’d better cut your hair short. Our school doesn’t __________ long hair.

A．approve of students wearing

B．approve students to wear

C．approve students wearing

D．approve of students to wear