用反证法证明命题“在直角三角形中，至少有一个锐角不大于45°”时，应先假设（　　）

A．有一个锐角小于45°

B．每一个锐角都小于45°

C．有一个锐角大于45°

D．每一个锐角都大于45°

It’s reported that ________ young  ____ to be rebellious against ____ parents’ instructions nowadays.

A．/, tends, his

B．the , tend, their

C．the , tend, his

D．a, tend, his