cheek前面用介词on，on the cheek 中文意思是，在脸颊上

He pecked her on the cheek as he went out.他出门时匆匆轻吻了一下她的面颊。

He gave me a little peck on the cheek.他在我脸上轻轻一吻。

He kissed her chastely on the cheek.他在她的脸上留下了一个纯洁的吻。