为什么煤层注水能够弱化冲击地压？
参考答案：
水的物理化学作用能够改变煤的物理力学性质，降低煤层的冲击倾向和应力状态；因而煤层注水能够弱化冲击地压。
小题1: Miss Ding lives in .
A. Hotel Eiffel B. Hotel Bank C. Hotel Park
小题2: The hotel is .
A. in the park B. on the left of the bank C. near the bank
小题3:Which bus can’t reach the hotel?
A. Bus 705. B. Bus 18. C. Bus.47.
小题4: If Miss Ding is lost, she can .
A. call her friends
B. wait until the light is green
C. call the hotel at the phone number on the card
小题5:Which of the following is true?
A. Open the door when the red light is on.
B. The card can be used to open the door.
C. Miss Ding can keep the card after he checks out.
什么叫体积密度？
