选B。saw强调的是看到的结果,而watch指的是看的过程,就像watch TV,你眼睛一直盯着屏幕,和题上所说的注视车一样,而非强调看见car这个结果;notice是注意到,observe是观察,注意到 I observed him going out. (与上题不同,这里强调看见他的结果)附:watch:1.看, 观察 She sat there watching, but said nothing.她坐在那里看着, 但没说什么。I often watch television in the evening.我通常在晚上看电视。Just watch what will happen when I press the button.看着, 我按按钮会发生什么事情。She watched the children play table tennis.她看孩子们打乒乓球。Many people like to watch others playing games.许多人喜欢看别人比赛。2.守卫[保护], 留心, 注视 The nurse watched to see what would happen.护士注意着会发生什么情况。She watched his face anxiously.她焦急地注视着他的脸。及物动词 vt.1.注意, 当心 Watch that he doesn't cheat you.注意别让他骗了你。2.监视 The policemen watched the guy for several days.警察监视那家伙好几天了。3.守候,等待4.照看;照料(婴儿等);看管(羊群等) The girl watched the baby yesterday afternoon.女孩昨天下午照看了小宝宝。notice:1.注意She pretended not to notice.她假装没看见。I didn't notice you when you passed by.你走过时, 我没有注意到你。We noticed how to make the experiment.我们注意如何做这个实验。The teacher noticed that one student was missing.老师发现一个学生不见了。I noticed how she did it.我注意到了她是怎么做这件事的。I didn't notice you enter.我没注意到你进来。I noticed the man leaving the house.我注意到那人离开这栋房子。He noticed the situation changed.他发现形势已经变了。observe:1.观察; 研究He observes carefully but says little.他总是仔细观察, 很少说话。及物动词 vt.1.看到; 注意到Didn't you observe the difference?难道你没有看出差别?We observed that it had turned cloudy.我们注意到天已经变阴了。We have never observed him do otherwise.我们从未看到他有不同的做法。Thousands of people observed the ship leaving the harbour.数以千计的人观看了轮船离港下水的情形。2.遵守; 遵循They faithfully observed the rules.他们忠实地遵守规则。3.评论[述]; 讲He observed that the house seemed to be too small.他说那房子似乎小了一点儿。