----Another cup of tea? That’s your third since lunch.
----Yeah, well, I all night preparing for my history exam. I can hardly keep my eyes open.
A. have stayed up
B. stayed up
C. have been staying up
D. will stay up
网友回答
A. have stayed up
(答案→)B. stayed up
C. have been staying up
D. will stay up
解析：考查时态：句意：--还要一杯茶？这是午饭后的第三杯了。--是的，我整晚都熬夜准备历史考试。我眼睛都睁不开了。从That’s your third since lunch.说明现在是午饭后了，那熬夜是在晚上，属于过去时间，用一般过去时，选B。