焊条电弧焊T形接头平角焊时，（）决定焊接层数与焊道数。
A.试件厚度
B.焊脚尺寸
C.焊条种类
D.两试件夹角
参考答案：B
The policewoman believes that Derek gave a reasonably _______ account of what had happened to the poor family during the robbery.
A．informal
B．potential
C．constant
D．accurate
弧坑中常含有（）等缺陷。
A.裂纹
B.缩孔
C.焊瘤
D.错边
