她的嘴唇很漂亮。

She has beautiful ___lips.

她用手指抹平了信封的开口边缘，确保完全密封。

She smoothed the ___lips of the envelope with her fingers to ensure it was completely sealed.

这些话从你嘴里说出来真让我吃惊。

I'm surprised to hear these words from your ___lips.

伤口的两侧需要保持清洁以防感染。

The ___lips of the cut need to be kept clean to prevent infection.