題目是
The office building ________ people walk in and out is the tallest buliding in the world.
解答是where
想請問為什麼不是which?
in and out 介系詞還存在句子中的情況下不是應該寫which嗎？

of which=where

in and out在此處應該只是副詞片語（in並非只有介詞功能，out更不一定），和walk搭配，有「進進出出」的意思。除非將題幹改為walk into and out of，into和of才是十足的介詞，才要選where