They'd like to know how they can get to the station

问题描述:

They'd like to know how they can get to the station
句中有一处错误,答案说把can改成could.
为什么呢?
句子前面的They‘d 是什么的缩写?

1.其实用can,could 在这里都可以,只是用could 语气委婉点而已
2.‘d like to = would like to...是个委婉的表达自己想法的一种说法