当采用（）电渣焊时，为适应厚板焊接，焊丝可作横向摆动。
A.丝极
B.板极
C.熔嘴
D.管状
参考答案：A
At the railway station, the mother waved goodbye to her daughter until the train was _______.
A．out f sight
B．out f reach
C．out f order
D．out f place
允许汽蚀余量应该比最小汽蚀余量大（）
A、0.2米
B、0.3米
C、0.3公斤
D、0.3兆帕
