nail in sb's/sth's coffin的nail是指甲还是钉子的意思?

nail in sb's/sth's coffin的nail是指甲还是钉子的意思? It's sb's sth? 造句：hard sb sth/sth to sb .sell sb sth/sth to sb lend sb sth/sth to sb serve sb sth/sth to sb s造句：show sb sth/sth to sb .offer sb sth/sth to sb .take sb sth/sth to sb .owe sb sth/sth to sb.teach sb sth/sth to sb.pass sb sth/sth to sb .tell turn sb's back on sth/sb sb.'s sth.和 sth.of sb.哪个正式 什么时候用sth.of sb.什么时候用sb's sth 有没有 borrow sb sth 或 borrow sb's sth sth.be sb.'s favourite=sb.() sth.() This is sb's sth中对sb's提问 某人代替某人做某事有几种说法我可不可以说sb.replace sb.to do sth.sb.substitue sb.to do sth.sb.take the place of sb.to do sth.sb.take one's place to do sth.sb.do sth.in place of sb.sb.do sth.instead of sb. in sb’s in sb's absence take sb's place to do sth sb.need sth.(三单时need加不加s) sth.cost(s) sb.+some money造句 what's the matter with sb./sth, let's sb to do sth还是doing sth lt's easy for sb.let sb.do sth.