Ifyouarewalkingawayfromaclocktower，youwillhearthetickingoftheclockfadetoapoint________itcannotbeheard.
C
译文：如果你从钟塔旁走过.你将会听到滴答声，直到你走远。此题考查定语从句。 where 在定语从句中做地点状语，先行词是 a point。
______ of a sentence depends on the context in which the sentence is uttered.
Thisisanimportantproblem_______toofewsocialscientistshaveresearched.
A linguistic theory is constructed about what ______ is and how it works.