在单元体的上下左右四个侧面，只有剪应力，而无正应力的情况，称为平面纯剪应力状态。
参考答案：对
The latest unemployment figures will _______ next week
A．declare
B．be declared
C．be announced
D．broadcast
They enjoyed piano.[ ]
A. play
B. playing
C. playing the
D. to play a
