It is not decided ________ the conference will be held.
C
A什么B哪一个C什么时候D(无词义)
Hesaidthatthegroup________himaletterandaskedhimtogothereforaninterview.
Thisisanimportantproblem_______toofewsocialscientistshaveresearched.
Alinguistictheoryisconstructedaboutwhat______isandhowitworks.
A linguistic theory is constructed about what ______ is and how it works.