1.I can remember all the telephone numbers after ----- them

1.I can remember all the telephone numbers after _____ them just once.
A.see B.saw C.seeing D.to see
2.______ notes can help you learn English.
A.Take B.To take C.Taking D.Took
3.Then you'd better do something about it,_____?
A.didn't you b.Hadn't you C.don't you D.haven't you
我的选择是1.C---after是介词,后面跟ing形式,after doing sth；选A的话句子应为after I see ...
2.C---动名词taking notes短语作主语;
3.B---you'd better=you had better