注意 + 到 + Object/Clause
注意 (zhùyì) is a verb meaning "to pay attention to" or "to notice," used when someone directs their awareness toward something. It can take a noun object or be followed by 到 to indicate becoming aware of something.
过马路的时候一定要注意安全。
Guò mǎlù de shíhòu yīdìng yào zhùyì ānquán.
You must pay attention to safety when crossing the street.
我注意到他今天的表情有点不对劲。
Wǒ zhùyì dào tā jīntiān de biǎoqíng yǒudiǎn bú duìjìn.
I noticed that his expression today seemed a bit off.
上课时请注意听老师讲话。
Shàngkè shí qǐng zhùyì tīng lǎoshī jiǎnghuà.
Please pay attention and listen to the teacher during class.