力臂是指()
A.支点到力点的水平距离
B.支点到阻力点的水平距离
C.支点到力点的垂直距离
D.支点到阻力点的水平距离
E.力点到阻力点的垂直距离
参考答案:C
—I wonder _____.
—Zebras. [ ]
A. what do they call these animals
B. how they call these animals
C. what they call these animas
D. how do they call these animals
下面是实验室制取氨气的装置和选用的试剂,其中正确的是( )
A.
B.
C.
D.