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.
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.
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).
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.