碳弧气刨下列金属材料中需采用直流交接的有（）。
A、碳钢
B、低合金钢
C、铸铁
D、不锈钢
参考答案：A, B, D
The young man _____ the car hoping to arrive at the station to meet his girlfriend on time.
A．gave up
B．sped up
C．turned up
D．picked up
法定资本制
