柠檬太酸了，他不由得皱起了脸。

The lemon was so sour that he ___puckered his face.

她皱着眉头，嘴唇因为酸柠檬而皱了起来。

She frowned, and her lips ___puckered at the sour lemon.

她皱眉时，额头会出现细小的皱纹。

When she frowns, tiny ___puckers appear on her forehead.