绝缘杆(棒)应()存放在支架上或悬挂起来,()接触墙壁。
A.水平,必须
B.水平,不得
C.垂直,必须
D.垂直,不得
参考答案:D
On seeing the funny scene,the audience ________. [ ]
A. burst into tears
B. burst into laughter
C. burst into cheers
D. burst out crying