已知一幅机械加工图纸的绘图比例是2:1,请问视图中尺寸标注的高度为56mm,则该产品的实际高度为()
A.42mm
B.168mm
C.56mm
D.84mm
参考答案:C
There were signs here and there, _____ visitors to look out for ______ rocks.
A.warning; fallen
B.warned; falling
C.to warn; fallen
D.warning; falling
蝙蝠依靠什么辨别方向?