路床不得有翻浆、弹簧（）等现象。
A.轮迹
B.起皮
C.波浪
D.积水
参考答案：B, C, D
— What do you think of the book I lent you yesterday?
— Oh, not too bad.It's not too difficult________. [ ]
A. to read
B. to be read
C. reading
D. being read
求累次积分
