Question

----Where do you work,Mr Black?---Iworked in a shop(which;where)sells food a

Answer 1

which
----Where do you work,Mr Black?-
----I worked in a shop which sells food.
先行词是shop，定语从句中缺主语，which 在从句中作主语，表示一般性的动作，故用现在时。
而where 在定语从句作状语，需要从句中有除了地点状语之外的完整句子结构，
如：I worked in a shop where most of customers preferred to go.
这里where等于to which，等于I worked in a shop which most of customers preferred to go to.

Answer 2

which

Answer 3

which

望采纳~谢谢~

追问

能具体说说吗？谢谢

追答

做从句的主语，要用代词
where引导状语从句啊，在句中不做成分的