a bike chain / the food chain

自行车链子/食物链

A chain is no stronger than its weakest link.

一环薄弱，全局必垮。

The prisoners are in chains.

囚犯戴着镣铐。

a chain of events / accidents / thoughts / misfortunes

一连串事件/事故/想法/灾难

a chain reaction

连锁反应

a supermarket chain

超市连锁店

Chain the horse to the tree.

把马拴在树上。