My sister is three years than I. She is young go to school.A. young; too; toB. younger; en

问题补充：

My sister is three years than I. She is young go to school.

A. young; too; to

B. younger; enough; to

C. younger; too ;to

D. young; so; that

答案：

A. young; too; to

B. younger; enough; to

(答案→)C. younger; too ;to

D. young; so; that

解析：考查比较级和固定句型。句意“我妹妹比我小三岁，她太小了还不能上学。”than提示用形容词的比较级，排除A、D；enough放在做日常的后面，排除B。too... to“太......而不能做......”。故选C。