2．(2011全国高考)When Alice came to，she did not know how long she ______ there.
A．had been lying B．has been lying
C．was lying D．has lain
解析：句意：当艾丽斯醒来时，她不知道自己在那儿躺了多久。根据时态一致的原则，可排除B、D两项；由she did not know how long...可知应用过去完成进行时，表示持续发生的动作。
答案：A
3．(2011山东高考)When I got on the bus，I ______ I had left my wallet at home.
A．was realizing B．realized
C．have realized D．would realize
解析：句意：当我坐上公共汽车时，我才意识到我把钱包忘在家里了。根据句意知when引导的时间状语从句的谓语动词表示的动作和主句的谓语动词表示的动作同时发生，且从句用一般过去时。
答案：B
4．(2011江苏高考)The fact that so many people still smoke in public places ______ that we may need a nationwide campaign to raise awareness of the risks of smoking.
