It was several years I realized David had lied to me.A. when; thatB. that; whenC. befor

问题补充：

It was several years I realized David had lied to me.

A. when; that

B. that; when

C. before; that

D. until; why

答案：

A. when; that

B. that; when

(答案→)C. before; that

D. until; why

解析：C句意：过了几年我才意识到大卫向我撒了谎。It is/was＋一段时间＋before...表示“过了多长时间才……”；第二空，realized后的从句不缺成分，故用that引导。