昏迷者气管切开（）。

A．有利于防治脑水肿

B．有利于呼吸道通畅

C．有利于促进恢复

D．有利于防止颅内压突然增高

E．有利于防止继发性感染

—Mr Wang’s never been to Canada , has he?

—________. He went there on business last week.

A．No , he hasn’t

B．Yes , he has

C．No, he has

D．Yes, he hasn’t