3.Although he is __________ his late seventies,he is still very healthy.A.at B.on C.by D.in

3.Although he is __________ his late seventies,he is still very healthy.A.at B.on C.by D.in
3.Although he is __________ his late seventies,he is still very healthy.A.at B.on C.by D.in

3.Although he is __________ his late seventies,he is still very healthy.A.at B.on C.by D.in
选D,这里的 seventies是一个时间段,所以和at the age of seventy不一样,所以应该用in

at one's seventies在某人70岁

D