调速器滑环低限行程不足，会引起调速汽门不能全开，带不上满负荷
参考答案：对
The idea of fish being able to produce electricity strong enough to light a lamp is almost unbelievable, _____ several kinds of fish are really able to do this.
A．therefore
B．and
C．then
D．but
无缝道岔维修作业，必须严格控制作业轨温。转辙和心轨部分长度范围内作业轨温，不应超过实际锁定轨温+（）℃。
A、5
B、10
C、15
