采用比较法来测量轴承间隙时,下述不正确的是()。
A.用外径千分尺测轴颈直径
B.用内径千分尺测轴瓦直径
C.径向最大值为D-d
D.测量位置可任意
参考答案:D
The foreigners _______ England, but they speak Chinese very well. [ ]
A. come in
B. come out
C. come from
D. come back
如果卖出50千克苹果表示为-50千克,那么+20千克表示______.