胸小用英语怎么说

"Small chest" in English is commonly referred to as "small breasts". The phrase comes from the anatomy of the human body, specifically the chest area where the breasts are located.

Examples:

"She is self-conscious about her small breasts." (她因为胸部小而不自信。)
"He prefers women with small breasts." (他更喜欢胸部小的女性。)
"She had breast augmentation to increase the size of her small breasts." (她做了隆胸手术来增加她小胸部的大小。)

It's worth noting that it's not respectful to comment on someone's body size or shape, therefore, it's best to avoid using this phrase in a negative or judgmental way.