用所给单词的适当形式填空：Mybrother______（study）inYuhongPrimarySchoolwhenhewas10yearsold.LastmonthI______（learn）howtoswim.Wemust______（learn）fromthegreatpeople.（）Mymothertellsmetopractice______the

　　用所给单词的适当形式填空：

　　Mybrother______（study）inYuhongPrimarySchoolwhenhewas10yearsold.

　　LastmonthI______（learn）howtoswim.

　　Wemust______（learn）fromthegreatpeople.

　　（）Mymothertellsmetopractice______thepianofortwohoursaday.

　　A.toplayB.playC.playingD.played

　　（）I'msorrytokeepyou_______forsuchalongtime.

　　A.towaitB.waitingC.waitedD.wait

　　最好能解释、分析原因.