you eat the correct foods be able to keep fit and stay healthy.A. Only if … will youB. O

问题补充：

you eat the correct foods be able to keep fit and stay healthy.

A. Only if … will you

B. Only if … you will

C. Unless … will you

D. Unless … you will

答案：

(答案→)A. Only if … will you

B. Only if … you will

C. Unless … will you

D. Unless … you will

解析：本题考查的是虚拟语气的用法。当only放在句首，修饰状语从句、副词或介词短语时，主句的谓语要部分前置，构成部分倒装。其记妙语是：only位句前，状从、副、介短，部分谓提前。