单项选择题
Generally speaking，the most favorable bottom for anchoring is（）.
A.very soft mud B.rocky C.a mixture of mud and clay D.loose sand
单项选择题 As a last resort，a tourniquet can be used to（）.
单项选择题 An uncontrolled flow of gas，oil，or other well fluids into the atmosphere is called a（）.
单项选择题 All the traces are（）old ones.
