煤层的（）是直接覆盖在煤层顶板上的岩层。
A、伪顶
B、直接顶
C、老顶
D、假顶
参考答案：A
— How are you getting on with your work?
— Oh, I am sorry. Things aren't going so well as _____. [ ]
A. plans
B. planning
C. planned
D. to plan
反渗透在调试过程中要求进水压力不得大于（）
A、1.8MPa
B、1.6MPa
C、2.0Mpa
