You must notice the emergency exit is when you enter the building.
A. which
B. where
C. what
D. in which
网友回答
A. which
(答案→)B. where
C. what
D. in which
解析：考查宾语从句。本题中的宾语从句where the emergency exit is是作为动词notice的宾语，where引导起这个宾语从句，并在句中作为表语。句意：当你进入大楼的时候，你一定要注意到紧急出口在哪里。故B正确。