当接头坡口表面铁锈等难以清理干净时，应选用抗裂性能好的碱性焊条。
参考答案：对
As reliable parents, they never ______ to give their son what he is promised.
A．expect
B．intend
C．manage
D．fail
常用的纵向磁化方法也就是通常所说的螺线管式线圈磁化方法
