高级抹灰表面平整度允许偏差（）mm.
A.2
B.3
C.4
D.5
参考答案：B
草履虫在水中旋转运动是靠 [ ]
A．食物泡
B．细胞膜
C．细胞质
D．纤毛
Don't be late again, _____ you will be punished. [ ]
A. because
B. but
C. or
D. though
