【题目】By 17:30, _______ was almost closing time, nearly all the products had been sold.
A. what B. when
C. which D. that
在线课程【答案】C
【解析】C。解析： “____ was almost closing time”是个非限定性定语从句，且从句内缺少主语。所以用关系代词which. D项that不用于非限定性定语从句中。句意：到了几乎是关门时间的17:30，几乎所有的油画才售完。