她在忧虑时仍然会吸吮大拇指。

She still sucks her thumb when she's worried.

《牛津词典》

Piaget's example would be a baby who's used to sucking on a breast might come to suck on a bottle or on a rattle.

皮亚杰举例说,一个习惯吸吮乳房的婴儿,可能会去吸吮奶瓶或是拨浪鼓

耶鲁公开课 - 心理学导论课程节选

A baby will form his mouth differently depending on what he's sucking on.

婴儿会因为吸吮物体的不同,而改变他的嘴型

耶鲁公开课 - 心理学导论课程节选