单层滤波器整体吊装应在两端（）控制，防止摆动过大。
参考答案：系绳
Being a doctor is one of the few professions＿＿＿＿if you make a mistake，it can mean somebody's life．
A．that
B．which
C．when
D．where
牵引电机换向器上火花较大的原因可能有哪些？
