can't help（情不自禁）后接to do还是doing

接动名词doing，但can't help but后接动词原形。

1. This cinema is so impressive that we can'thelp crying. 这影片如此感人以至我们禁不住流下泪来。
来自《简明英汉词典》
2. When our country calls us for help, we can'thelp but go. 当祖国需要我们时，我们必须尽力。
来自《简明英汉词典》
3. When a close friend dies, we can'thelp but feel sad. 当一位亲密的朋友去世时，我们不能不难过。
来自《简明英汉词典》
4. She's a funny girl, yet you can'thelp liking her. 她很滑稽，但你禁不住会喜欢她。
来自《简明英汉词典》
5. I can'thelp grinning at the funny things the child says. 听到孩子说的那些趣事，我忍不住笑了。


如果接不定式，表示不能帮助做某件事。help表示本义。

can’t help doing sth=禁不住做某事，情不自禁地做某事；can’t help to do sth=不能帮助做某事

应该是：
can't help doing sth 禁不住做某事
I can't help laughing every time I think of that.
每次一想起那件事,我就会忍不住笑起来.

can't help doing sth 固定搭配