The nurse is developing a teaching plan for a client diagnosed with osteoarthritis. To minimize injury to the osteoarthritic client, the nurse should instruct the client to

A. install safety devices in his home.
B. wear comfortable shoes.
C. get help when lifting objects.
D. wear protective devices when exercisin

在开采煤层群时，如果矿井瓦斯涌出量主要来自邻近层，则可由开采层向一定距离的顶（底）板其它煤层中打钻抽放，这种方法叫（）。