When his parents saw him fall down是不是 复合句 要不要saw 和 fall为什么都用

When his parents saw him fall down是不是 复合句 要不要saw 和 fall为什么都用 第一题：His fellow workers saw him fall down and blood came out .I,around,an,man,when,was,down,fall,walking,the,saw,station, i saw a piece of glass fall down when i walked past the offi I saw a boy fall off a bike,这句话saw用了过去式,为什么fall不用? 是“I saw an old man fall down”还是“I saw an old man fell down” i saw her fall into l saw a little boy fall into the water.为什么不用fell,而用fall?为什么不 he saw a star fall from the sky and dissappeared 这里fall是不是错了 l saw a little boy fall into the water.是用fall还是falling? fall和fall down有什么区别?为什么有的时候说water fall from the clouds Someone saw him ______ (fall) off the horse just now.填was fa