问题补充:
he was seriously ill, I wouldn’t have told him the truth.
A. If I knew
B. If I know
C. Had I known
D. Did I know
答案:
A. If I knew
B. If I know
(答案→)C. Had I known
D. Did I know
解析:考查含有if条件状语从句的虚拟语气。根据wouldn’t have told,可知指的是过去情况,所以if从句要用过去完成时态,即if I had known he was seriously ill,助动词had可以提到句首,省略if ,构成部分倒装,即had I known he was seriously ill。所以选C。