机械辅助通气的作用有()
A.纠正严重呼吸性酸中毒
B.维持有效的气体交换
C.减少肺内分流
D.缓解呼吸肌疲劳
E.预防术后肺不张
参考答案:A, B, C, D, E
Everything he _______ to his country.
A.had donated
B.had been donated
C.had to be donated
D.had was donated
I know nothing about the young lady ___________ she is from Beijing.
A.except
B.except for
C.except that
D.besides