Thisisanimportantproblem_______toofewsocialscientistshaveresearched.
A、whichD
into which 引導的是 problem 的定語從句。 which 指代 problem ，into 與 research 搭配。
Theengineer______myfatherworksisabout50yearsold.
Thereply,whenitfinallycame,was________thenegative.
Fromthesociolinguisticperspective,aspeechvarietyisnomorethanadialectalvarietyofalanguage.
Thevolunteerswouldrathergobytrainthan________.
_______isafactthatEnglishisbeingacceptedasaninternationallanguage.
