下列运算正确的是[ ]
A．x2+x3=x5
B．x8÷x2=x4
C．3x﹣2x=1
D．（x2）3=x6
答案：D
Don't let me _____ your decision. You should make your own decision from now on.[ ]
A. retum
B. volunteer
C. include
D. influence
Ⅳ、Ⅴ类围岩地段不得布置（）。
A.铸铁管
B.钢衬钢筋混凝土管
C.钢管
D.钢筋混凝土岔管
