RQD指岩体的质量指标，其确定方法为（）。
参考答案：钻孔的单位长度大于10厘米的岩心所占的比例
The map is one of the best tools a man has ________ he goes to a new place. [ ]
A. whenever
B. whatever
C. wherever
D. however
In Germany, you shouldn’t arrive late to a dinner party; you should always be ___.
A．on time
B．at times
C．in time
D．for a time
