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