来自陈其国的问题
HilloftenattendspubliclecturesattheUniversityofLondon,chiefly__hisEnglishA.toimproveB.improvingC.tohaveimprovedD.improved老师说是C，为什么不是A？
HilloftenattendspubliclecturesattheUniversityofLondon,chiefly__hisEnglish
A.toimprove
B.improving
C.tohaveimproved
D.improved
老师说是C，为什么不是A？
