swimming双写m是因为swim只有一个元音字母+辅音字母的构词，rain当中有两个元音字母+辅音字母，不能双写n。
swimming双写m，为什么raining不双写n
因为rain不是重读闭音节。
People were swimming in the ocean despite the hurricane warning.
尽管有飓风警报，人们仍然在大海里游泳。
I shall still go ， notwithstanding the rain .尽管下雨，我仍然要去。
Shut the window for fear that it may rain .恐怕会下雨，把窗户关上。
Suppose it rained ， we would still go .假如下雨的话，我们还是要去。
It 's damp and cold ， i think it 's going to rain .我看是要下雨了。
In case it should rain ， do n't expect me .如果天下雨，我就不来了。
