用所给动词的适当形式填空
小题1:We will visit the farm if it ____________ (not rain) tomorrow。
小题2:Gravity is a force that stops us from____________ (float) in the air.
小题3:Our home town ___________(change) a lot over the years.
小题4:The train _______________( leave) already when we arrived.
小题5:I _________________( do) my homework when the light went out yesterday.
