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。
ThedivisionofEnglishintoOldEnglish,MiddleEnglish,andModernEnglishisnonconventionalandnotarbitrary.
Youngerchildrenarecurious________howthingswork，andmanyofthemwanttotakeaparteverythingwithintheirreach.
Theconclusionfromthestudyisnotdefinite;itisjust________.
Countrylifeisbetterthancitylife________itoffersfreshairandnoiselessenvironment
Searle'sclassificationofillocutionaryactsisbasedontheclassificationofperformativeverbs.
