It___(seem)that the children have changed a lot.答案是seems.请问seemed为何不可呢

题目

It___(seem)that the children have changed a lot.答案是seems.请问seemed为何不可呢

答案

It seems (seem)that the children have changed a lot.
如果是【seemed】的话,后面就应该用had changed
时态要往前推一格
有不会的可以再问我