须使列车退回时，行车值班员要关闭有关信号、办理进路后，向列车司机显示引导手信号令列车退行。
参考答案：对
翻译句子，体会sharp在句中的意义.
1. It was very sharp of you to see that.
2. Emma has a sharp tongue.
3. The photograph is not very sharp.
4. Accidents often happen where there are sharp bends.
5. Please be here at seven o'clock sharp.
6. Sharks have sharp teeth.
头痛宁胶囊的卖点（）
A.显著降低偏头痛发作时血浆CGRP（降钙素基因相关肽）含量，阻断脑膜血管异常扩张，有效治疗偏头痛
B.促进脑内阿片肽表达，调节中枢内源性镇痛系统，有效止痛
C.治疗偏头痛、紧张型头痛，一疗程总有效率81.93%（入组844例）
D.中枢镇痛、镇静作用
