对于地下房间、无窗房间或有固定窗扇的地下房间，以及长度超过20m且无自然排烟的疏散走道，或有直接自然通风，但长度超过40m的疏散内走道，应设()设施。

According to the first two paragraphs, bankers______.A．are depriving the masses of their interestB．are also victims of the previous recessionC．bear some responsibility for the past crisisD．are criticised for inconsistent work standards 点击查看答案

OSI开放系统互联参考模型把整个网络划分为()个层次。

A.4
B.5
C.6
D.7

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