They gave the students a warm welcome.如果将题目的句子改为被动语态,那么:The students were given a warm welcom by them.

问题描述:

They gave the students a warm welcome.
如果将题目的句子改为被动语态,那么:
The students were given a warm welcom by them.

没错
除了那个welcome...你打了welcom,应该是手快打错而已

完全正确,可以这样改.