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。