The adverb 不禁 "can’t help"
The adverb 不禁 
indicates that someone can’t stop themselves from doing something.
In a sentence, it is placed before a predicate expressed by a verb.
indicates that someone can’t stop themselves from doing something.
In a sentence, it is placed before a predicate expressed by a verb. Pay attention
不禁 cannot be followed by a negation.
It is used in written language.
Examples
看到这里，我不禁感动得流下了眼泪
I was moved to tears when I saw it
kàndào zhèlǐ, wǒ bùjīn gǎndòng de liúxià le yǎnlèi
我不禁回忆起第一次跟她见面的场景
I can't help but remember the first time I met her
wǒ bùjīn huíyì qǐ dì yí cì gēn tā jiànmiàn de chǎngjǐng
苏珊不禁有点儿恼火
Susan couldn't help but get angry
sūshān bùjīn yǒudiǎnr nǎohuǒ