can't help do sth/can't help to do sth./can't help doing sth 有什么区别?特别是前两个的区别,要详解,谢谢

很好很全，我以前见过这问题。。
请看下面的试题：He knows nothing about it, so he can’t help _________ any of your work.
A. doing B. to do C. being doing D. to be done
【分析】此题答案应选B。比较以下结构：can’t help to do sth = 不能帮助做某事can’t help doing sth = 禁不住做某事，情不自禁地做某事请看例句：I can’t help to do it. 我不能帮忙做这事。He couldn’t help to wash the clothes. 我不能帮忙洗衣服。She couldn’t help smiling. 她禁不住笑了起来。She couldn’t help envying Helen. 她不由得 不妒忌海伦。We cannot help being impressed by their zeal. 我们不由得不被他们的热情感动。英语有时还可说can’t help somebody doing something不能使某人不做某事。如：I couldn’t help him saying that. 我不能让他不这样说。We couldn’t help them seeing us. 我们无法让他们不看到我们。She could not help the tears of rage rolling down her face. 她止不住她愤怒的眼泪顺着面颊流下来。
又如下面一题，答案也是 B：She can’t help _________ the house because she’s busy making a cake.A. cleaning B. to clean C. cleaned D. being cleaned
再请看以下试题：
While shopping, people sometimes can’t help _________ into buying something they don’t really need.
A. to persuade B. persuading C. being persuaded D. be persuaded
此题应选C，句中的 can’t help 意为“禁不住”（注意根据句意用被动形式）。

can’t help to do sth = 不能帮助做某事can’t help doing sth = 禁不住做某事，情不自禁地做某事
ms没有can't help do sth这个结构啊

正确来说,
can't help do something:不能帮忙做
can't help doing:忍不住...
以前一直以为can't help to do是正确句型,来到北美看了多少书写了多少文章才意识到can't help do才是对的.
不过如果要对国内的考试交待,还是国内怎么教的就怎么答吧.