留心 (liú xīn): để được cẩn thận

When crossing the road, you must pay attention to the traffic, especially at night when visibility is poor.

His mother reminded him several times that when looking for a job, he must be careful about the company's background and reputation.

The doctor advised him to watch for any allergic reactions while taking the medication.

She usually pays attention to what kind of coffee her colleagues like, so she can help every time they order together.

When studying classical Chinese, you need to pay attention to words whose meanings differ between ancient and modern times; otherwise, it's easy to misunderstand.

Before signing the contract, he paid close attention to every clause and indeed found a detail that was unfavorable to his side.