This is an important problem _______ too few social scientists have researched.
A、whichD
intowhich引导的是problem的定语从句。which指代problem，into与research搭配。
Hetalkedalotaboutthingsandpersons________theyrememberedintheschool.
_______forthefreeticket,Iwouldnothavegonetoseefilmsooften.
Country life is better than city life ________ it offers fresh air and noiseless environment
Weather _______, we ’ll go out for a walk.
Acompoundisthecombinationofonlytwowords.
