Thisisanimportantproblem_______toofewsocialscientistshaveresearched.
A、whichD
into which 引导的是 problem 的定语从句。 which 指代 problem ，into 与 research 搭配。
Werefertothelimitedrangeofsoundsasthephonicmediumoflanguageandindividualsoundswithinthatrangeas______.
Fromthesociolinguisticperspective,aspeechvarietyisnomorethanadialectalvarietyofalanguage.
______ofasentencedependsonthecontextinwhichthesentenceisuttered.
Lyingundertheskull,thehumanbraincontainsanaverageoftenbillionnervecellscalled______.
Thevolunteerswouldrathergobytrainthan________.
