锅炉风机按其工作原理不同分为（）和（）两大类。
参考答案：离心式；轴流式
Maggie wanted an evening job that would allow her to ______ her son during the day.
A．look at
B．look around
C．look after
D．look out
导致长期昏迷和持续性植物状态最为常见的原因是（）
A.脑出血
B.脑梗死
C.脊髓损伤
D.颅脑损伤
E.蛛网膜下隙出血
