I mustn't trouble if he doesn't come tonight.是什么意思？

I mustn't trouble if he doesn't come tonight.

今晚他若不来, 我就不用费心劳神了。

trouble

n. 麻烦，烦恼，故障，动乱；vi. 费心，烦

例句
Every time I fluffed a line Lenny got me out of trouble with a brilliant ad-lib.
每次我台词出错时，伦尼都通过机智的临场发挥帮我解围。

if

conj. 如果，倘若，即使，〈口〉是否，假设；n. 条件，设想；

例句
She was old enough to absent herself from the lunch table if she chose...
她长大了，可以自己做主不来吃午餐了。

he

pron. 他，它，一个人；n. 雄性动物；

例句
Logic had prevailed and he had abandoned the idea.
最终理智占了上风，他打消了那个念头。

come

vi. 来，开始，出现，发生；vt. 做，装扮…的样子，将满（…岁）；int. 嗨！；

例句
I've come looking for a bit of advice.
我特来讨教。

tonight

n. 今晚，今夜；adv. 在今晚；

例句
He will announce tonight that he is resigning from office...
他将于今晚宣布辞职。