一个圆的半径是5cm,直径是______cm.
5×2=10(cm),
答:它的直径是10cm;
故答案为:10.
调速器是通过改变蒸汽压力来调节速度的。
The geometric center of the waterplane area is called the().
A.center of buoyancy
B.center of gravity
C.metacenter
D.center of flotation