it is的缩写,it has的缩写;
例句:
I think it's time you had a word with him.
我觉得你该跟他谈谈了。
"I can't see it's any of your business," he raged.
“这根本不关你的事,”他生气地说。
Any escape, once it's detected, sets off the alarm.
一旦发现有泄漏,警报就会响起来。