下列各组数中，相等的一组是[ ]
A．+32与+22
B．﹣23与（﹣2）3
C．﹣32与（﹣3）2
D．3×22与（3×2）2
B．
Tom got all A's _____ he spent most of his time studying. [ ]
A. if
B. before
C. because
D. although
施工技术准备时，选择施工机械时应注意什么？
