He looked quite healthy though he was .
A. in seventy
B. in his seventy
C. at seventies
D. at the age of seventy
网友回答
A. in seventy
B. in his seventy
C. at seventies
(答案→)D. at the age of seventy
解析：“他70多岁时”应该是in his seventies，A、B、C三项都不正确；at the age of seventy意思是“在他70岁时”。