建筑防水按设防方法分为（）。
A.复合防水
B.卷材防水
C.构造防水
D.刚性防水
参考答案：A, C
an+1·an﹣1÷(an)2 的值是[ ]
A．1
B．0
C．﹣1
D．±1
Some minerals are quite common, others are regionally ________, and still others are rare on the earth.[ ]
A. attributed
B. distributed
C. contributed
D. scattered
