It has rained for three days 这个用法对吗?rain是动态动词,可以用于带‘for’的现在完

这三种说法都可以.
It rained for 40 days during the flood.
It has rained for days and the fields are flooded.
rain虽是动词,但可持续,可用for表现在完成时,以强调结果