脑疝致命的原因是（）
A.脑脊液循环障碍
B.脑干受压
C.小脑受压
D.颅内重要血管受压
E.大脑皮层受压
参考答案：B
While Mr Smith was on vacation last month, he asked his secretary to _____ the business of his company. [ ]
A. have an eye for
B. have eyes for
C. keep an eye on
D. keep eyes on
鉴别急性与慢性呼吸衰竭，哪项是正确的（）
A.有无发绀
B.有无缺氧及二氧化碳潴留
C.起病缓急
D.有无肺气肿
E.有无呼吸困难
