They arrive home early.

他们到家很早。

youdao

If they had left home early this morning, they would arrive in half an hour.

如果他们今天一早就离开家的话，再过半小时他们就该到了。(从句说明过去，主句说明将来。)

youdao

If they had left home in early morning, they would arrive in half an hour.

要是他们一大早就离开家的话，再过半个小时就该到了。

youdao

If they had left home in early morning, they would arrive in half an hour.

要是他们一大早就离开家的话，再过半个小时就该到了。

youdao