I saw a boy fall off a bike,这句话saw用了过去式,为什么fall不用?

I saw a boy fall off a bike,这句话saw用了过去式,为什么fall不用? I saw a boy fall off the bike and hurt himself.还是I saw a boy l saw a little boy fall into the water.为什么不用fell,而用fall?为什么不 i saw a boy ()into the river.用fall还是falling? l saw a little boy fall into the water.是用fall还是falling? fall over a bike还是fall off a bike啊? he saw a star fall from the sky and dissappeared 这里fall是不是错了 i saw her fall into I saw a man saw a saw with a saw.这句话是什么意思? i saw a saw saw a saw. The boy was seen___(fall) off his bike a moment ago. 这句话为什么不用what而用where? i saw a buster keaton film where he had