Look at the clouds ,I think it ___(rain)

问题描述:

Look at the clouds ,I think it ___(rain)

填is going to rain.
表明事情等的发生之前含有酝酿的一个过程,有某种迹象会发生某事,只能用is going to rain
不能用will rain,will只表将来,没特殊含义.