The word 'can't' is contraction for 'cannot.' Combined with 'help' you are communicating something you are unable to control or having a hard time gaining a grasp for. This can be a physical or mental action. '

can't'这个词是'cannot'的缩写形式，和'help'搭配使用你可以交流一些你无法控制或者很难把握的事情，这可以是身体上或心理上的活动。

Here are some examples: 这里有一些例子： 

"I can't help thinking about it."

 我不禁想起它。

"I can't help shopping so much."

 我忍不住经常购物。

"I can't help working all the time."

 我忍不住一直工作。

"I can't help smiling when I see her."

 当我看到她的时候我忍不住笑了。

"I can't help eating so much."

 我忍不住吃太多了。

"I can't help loving you."

 我忍不住爱上你。

"I can not help biting my nails when I am nervous."

 当我紧张的时候我忍不住咬我的指甲。

"I can not help smoking when I have been drinking."

 当我喝酒的时候我忍不住会抽烟。

"I cannot help feeling so sad."

 我不禁感觉很悲伤。

"I cannot help remembering the things you did."

 我不禁想起你做过的事情。