研磨的切削量很小，每研磨一遍所能磨去的金属层不超过（）毫米。
A.0.002
B.0.02
C.0.001
D.0.01
参考答案：A
对一个已经排好序的序列进行排序，采用( )比较适宜。
A．冒泡法
B．直接选择法
C．直接插入法
D．归并法
Both Jim and Kate _____ in Beijing now. They both _____ from America. [ ]
A. is ; come
B. are ; come
C. is ; comes
D. are ; comes
