角度测量时,用较厚的钢板铺成平台,平台顶面最好高出地平面()左右,便于测量。
A.200mm
B.300mm
C.500mm
D.800mm
参考答案:C
— Did the door-keeper let you in?
— No. ____I tried to tell him I was your relative, he just didn’t believe me.
A.Whether
B.Whatever
C.No matter
D.However
微机用户可以采用()方法将自己的微机连入Internet。
A、一种
B、两种
C、三种
D、四种