contract in

The bodybuilders contracted their biceps in unison.

健美运动员们一起收缩肱二头。

The pupil of the eye dilates and contracts in response to light.

对光线出反应，眼睛瞳孔会大或缩小。

Metals contract in cold weather.

金属遇冷天气收缩。

Long-standing oesophagitis may be complicated by the formation of scar tissue that contracts and results in a narrowing (stricture) in the affected part of the oesophagus.

长期炎产生上伤痕附生物以致部分狭窄。