按两焊件位置，焊接形式可分为（）。
A.对接
B.T形连接
C.搭接
D.角部连接
参考答案：A, B, C, D
I could have offered you some help last weekend, but I _______ with my work at that time.
A．would be occupied
B．was occupying
C．had been occupied
D．was occupied
爆炸压力范围随燃料压力和温度的升高而（），其着火危险性增大。
A.变宽
B.变窄
C.不变
D.一会变宽一会变窄
