如果你明天没空，那么我们可以改天再约。

If you're not free tomorrow, ___then we can meet another day.

如果你饿了，那就吃点水果吧。

If you're hungry, ___then have some fruit.

先做完作业，那么你就可以看电视了。

Finish your homework first, ___then you can watch TV.