帮忙解决下面的几道英语选择题,初三的
1.Theworld_______ismadeupofmatter.
A.inthatweliveB.onwhichwelive
C.whereweliveinC.welivein
2.Ihavemanybooks,someof_____areonchemistry.
A.themB.thatC.whichD.those
3.Theastronautdidmanyexperimentsinthespaceship,_______muchhelpforknowingspace.
A.whichwethinkitisB.whichwethinkareof
C.ofwhichwethinkisD.ithinkwhichisof
顺便说明一下为什么..谢谢大家了.只有20分了.