persistent

She has been suffering from a persistent cough for over a month despite taking antibiotics.

(Chinese) 尽管服用了抗生素，她的咳嗽已经持续了一个多月。

The salesman was so persistent that I finally bought the vacuum cleaner just to make him leave.

(Chinese) 那个推销员非常缠人，我最后只好买下了那台吸尘器，好让他离开。