完形填空，阅读下面短文，掌握其大意，然后从各题所给的四个选项中，选出一个最佳选项。?

　　Last night I was driving from Harrisburg to Lewisburg, a 　　1　　 of about eighty miles．It was late and I was in a hurry．However, if anyone asked me how fast I was 　　2　　 , I'd say I was

　　not overspeeding．Several times I got 　　3　　 behind a slow-moving truck on a narrow road, and I was holding my fists tightly with 　　4　　．

　　At one point along an open highway, I 　　5　　 a crossroads with a traffic light．I was alone on the road by now, but as I 　　6　　 the light, it turned red and I braked to a stop．I looked left, right and behind me．Nothing．No cars, no suggestion of headlights, but there I sat, waiting for the light to 　　7　　 , the only human being for at least a mile in any 　　8　　．

　　I started 　　9　　 why I refused to run the light．I was not afraid of being 　　10　　 , because there was obviously no policeman around, and there certainly would have been no 　　11　　 in going through it．

　　Much later that night, after I 　　12　　 a group of friends in Lewisburg and climbed into bed near midnight, the question of why I'd stopped for that light 　　13　　 me．I think I stopped because it's part of a contract(合同)we all have with each other．It is not only the 　　14　　 , but also it is an arrangement we have, and we trust each other to 　　15　　 it：we don't go through red lights．Like most of us, I am more likely to be 　　16　　 from doing something bad by the social convention(传统习惯)that 　　17　　 it than by any law against it．

　　It's amazing that we ever 　　18　　 each other to do the right thing, isn't it? And we do, too．Trust is our 　　19　　 preference．

　　I was so 　　20　　 of myself for stopping for the red light that night．

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