chain是可数名词。

These chains seem fairly solid.这些链子看着挺结实。The dog is fastened to post by an iron chain .那条狗用铁索拴在柱子上了。She wore a locket hanging on a silver chain .她戴着银项链儿，坠着个挂盒。I was just going out to chain up the dogs .我正打算把狗拴上。I'm chained to my desk in london .我被套在伦敦的办公室里了。The polynucleotide chain is helical .多核苷酸键是螺旋形的。Her thoughts could not be chainedelsewhere .她的思想也不能被别的事物束缚住。The chain reaction is self-sustaining .连锁反应是自持的。The dog has got free from its chain .那狗挣脱链子跑了。The incident sparked off a whole chain of disasters .那件事惹出了一连串的灾祸。