化学岩和生物化学岩是由原始母岩风化后的（）物质构成的。
A.碎屑
B.溶解
C.有机
D.不溶残积
参考答案：B
She couldn't help, even though she tried not to,（）at the strange clothes her friend was wearing.
A. to laugh
B. laugh
C. laughing
D. laughed
多人扛运轨枕时，应分开来回地走行，以免相互干扰，前后两人至少间隔（）米。
A、6
B、5
C、8
D、7
