在灾难系统的建设国际标准中，批量在线数据库镜像或日志传输属于哪一层（）
A.3
B.4
C.5
D.6
参考答案：B
能被3整除的数，一定都是[ ]
A．整数
B．偶数
C．合数
In our own galaxy, the Milky Way, there are perhaps 200 billion stars, a small part of them probably have planets on which life is feasible.
A．a small fraction in which
B．a small fraction of which
C．a small fraction which
D．which a fraction of
