怎么理解drop off句中的含义.

落下,掉下,脱落：The book dropped off his hand。书从他手中掉下来。His button has dropped off。他的纽扣掉了。[口语]把…从车上卸下；(让…)下车,从(交通工具)上下来：Drop me off at next stop。请让我在下一个站下车。把…放在,把…放下；把…交给某处：to drop a letter off寄出一封信to drop the lanndry off把要洗的东西交给洗衣店Could you drop off the books at the library?你能把这些书顺便还给图书馆吗?(数量)减少,变少；下降；衰落；萧条；衰弱：Sales have dropped off。销售量已下降了。The membership of the club began to drop off。这个俱乐部会员开始减少。Flowers are dropping off。花在凋谢。(质量)下降,变差：The quality of work has dropped off since last month。自上月起,工作质量已下降了。[口语]入睡,睡着；打瞌睡：She was so tired that she dropped off in front of the television。她很疲倦,在看电视时打盹。He dropped off to sleep in the middle of the class。在上课过程中他睡着了。(一个一个地)走掉,离开,一一散去；消失：The attendance gradually dropped off。与会者一一散去。Her children have dropped off one by one。她的孩子们一个一个地离开了她。[口语]死去：The old woman dropped off in her sleep。这老太婆在睡眠中死去了。 再问： 看句子，谢谢 再答： 7-Eleven在美国是家非常有名的便利店。 They were eventually dropped off at a 7-Eleven store two hours from the farm。 他们最终在离农场有2小时路程之隔的7-Eleven便利店下车。