Grammar∣can't (couldn't) help + V-ing (忍不住); can't help but + V (不得不)

can't (couldn't) but + V 忍不住；不得不 I cannot but laugh. 我忍不住要笑。
I can't but do it. 我不得不做。
= I can't help but do it. = I can't help doing it.
= I have no choice but to do it.

can't (couldn't) help but + V 原型動詞 I cannot help but be sorry. 我不得不感到遺憾。
She couldn't help but keep crying. 她只是一直不停的哭。
Ms. Yeah couldn't help but be angry at what one of her co-workers said at the meeting.

can not help + V-ing I can't help having my report card burnt when I see it.
當我看到我的成績單時，我忍不住想把它燒了。
I can not help thinking you are selfish. 我不得不認為你很自私。
Since the pollution level is high today, people can not help breathing in car exhaust (廢氣).

She can't help but keep crying.

She can't help crying.= she can't but cry.

The article is so moving/touching that...
I can't help tearing.
I can't but tear.
I can't withhold my tears.
I can't hold back my tears.
my tears start to fill my eyes.