Look!There are a lot of children playing in the ground.为什么要用playing而不用are playing

Look!There are a lot of children playing in the ground.为什么要用playing而不用are playing
Look!There are a lot of children playing in the ground.为什么要用playing而不用are playing

Look!There are a lot of children playing in the ground.为什么要用playing而不用are playing
因为前面有 There are 所以再用一个are没有必要
There be .. doing .. 固定的用法
其实也可以把doing 看成定语. 修饰children

因为there be句型中 进行时态都直接用doing

表示正在发生的状态
而且前面有 are 了 再加are就是 双谓语了
是错误的!