承压含水层与开采煤层之间的隔水层能承受的水头值大于实际水头值时,可以带水压开采。
参考答案：对
John has great singing _____, but to become a real singer, he needs a lot of necessary training and practice. [ ]
A. privilege
B. potential
C. promotion
D. possibility
“不患寡而患不均”出自（）。
