（a-b）2•（b-a）3+（a-b）4•（b-a）
原式=（a-b）2•（a-b）3+（a-b）4•（a-b）=（a-b）2+3+4+1=（a-b）10．
采用栓钉作为组合梁的剪力连接件，当栓钉较弱时，极限承载力（）。
A、随栓钉直径和砼抗压强度等级增加而增加
B、随栓钉直径和抗拉强度增加而增加
C、随栓钉直径和砼抗拉强度等级增加而增加
D、只与栓钉强度有关
Which of the following statements concerning frontal movements is TRUE（）.
A.The temperature rises after a cold front passes
B.The barometric pressure rises when a warm front passes
C.A cold front generally passes faster than a warm front
D.A warm front usually has more violent weather associated with it than a cold front
