金属条板顶棚属于()的顶棚。
A.重型上人
B.重型不上人
C.轻型不上人
D.轻型上人
参考答案:C
Her mother ________ the girl to leave the house before she had finished her homework.[ ]
A. prevented
B. banned
C. forbade
D. prohibited
填砂裂缝支撑剂的性能要求包括()等。
A.悬砂能力强
B.粒径均匀,密度小
C.强度大,破碎率小
D.圆球度高