高中英语完成时---Haveyoubeenteachingheresincegraduation?---No,I____farmfor5years.A.workedB.haveworkedC.wasworkingD,hadworked为什么选A不选B?Cathyistakingnotesofthegrammaticalrulesi

　　高中英语完成时

　　---Haveyoubeenteachingheresincegraduation?---No,I____farmfor5years.

　　A.workedB.haveworkedC.wasworkingD,hadworked

　　为什么选A不选B?

　　CathyistakingnotesofthegrammaticalrulesinclassatSunshineSchool,whereshe___Englishforayear.?

　　A.studiesB.studied?C.isstudyingD.hasbeenstudying

　　为什么这个选D如果把Cathyis换成Cathywas是不是选B呢?为什么?

　　谢谢了!