根据发生在不同层位的冲击地压分为哪几种?
参考答案:(1)煤体(压缩型)冲击地压;
(2)顶、底板岩层(断裂型)冲击地压;
(3)断层(错动型)冲击地压等三大类型。
下列说法正确的是( )。 ①复利终值和复利现值互为逆运算 ②单利终值和单利现值互为逆运算 ③普通年金终值和偿债基金互为逆运算 ④普通年金现值和资本回收额互为逆运算
A.①②③
B.①②④
C.②③④
D.①②③④
_______ read newspapers for pleasure,but also to improve their minds. [ ]
A. Not only old men
B. Not only old men do
C. Not only do old men
D. Old men not only do