It was several yearsI finally realizedDavid had lied to me.A. when;thatB. that;whenC. befo

问题补充：

It was several yearsI finally realizedDavid 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：考查it构成的常用句型以及宾语从句的连接词。several years是时间段，不是时间点，后面不能接由when引导的从句;several years不能作时间状语，所以题干也不能是强调句型；根据句意分析，此处应表示：“过去了几年我才终于认识到……”。realized后面接宾语从句，这个宾语从句句意和句子成分完整，所以要用that引导。