在恒牙列中患龋率最低的牙齿是
A．下颌前牙B．上颌前牙C．上颌尖牙D．下颌尖牙E．下颌前磨牙
参考答案：A
The young lady prefers dressing up for a party to by others.
A．be noticed
B．noticing
C．having been noticed
D．have been noticed
钨极氩弧焊的钨极端部形状采用锥形尖端效果最好，电弧稳定，焊缝成形良好。（）
