61weknow,whenseniorstudentsfinishschool,mostoftheirrefe...
問題詳情：61weknow,whenseniorstudentsfinishschool,mostoftheirreferencebooks _62__(throw)away,whicharestillingoodcondition. 63agreatwasteitis!Isuggestthatstudentsshouldrecycleallthesebooks.Ontheonehand...