关于人工呼吸不妥的是

A．置婴儿仰卧位，头尽量后仰

B．一般采用口对口人工呼吸

C．幼婴可以口对口鼻人工呼吸

D．牙关紧闭者可以采用口对鼻人工呼吸

E．吹气与排气时间之比是2:1

One of the real services of the historical novel is not that it can be a substitute for history, but that it can be a(n) extension.

A. compliment
B. supplement
C. instrument
D. replacement