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阅读下面短文，掌握其大意，然后从1～25各题所给的四个选项中，选出一个最佳答案．

　Bill was a very good pilot(飞行员), He 　1　in the air force for several years, and had been very 　2　．Now he was sent to a small field in the forest, 　3　areoplanes were able to attack the enemy very easily, because it was 　4　the front line, but 　5　to fin/D．The forest trees were very tall and very close on all 　6　, so planes had to dive down steeply(急剧地)and then 　7　their dive very suddenly 　8　they hit the ground．Only the best pilots were able to 　9 　safely, and even some of those lost their planes and were killed because they 　10　the trees or the ground．

　　　After Bill had arrived, he was not 　11　until he was able to fly closer to the trees than 　12　pilots, and soon all the pilots who used that field were trying to 　13　each other at flying 　14　over the forest．Every time one of their aeroplanes came back 　15　an attack on the enemy the other pilots 　16　to run outside and watch, to see 　17　near the trees its pilot took it． If he 　18　in taking it very near, they laughed and shouted and bought him beer at the bar when he got 　19　．

　Bill soon 　20　exactly how near he was able to go 　21　, and then one day he flew so close to the tops of the trees that some of the branches scratched the 　22　of his plane．The other men in the plane seemed rather 　23 　, but Bill only laughed and landed the plane without any trouble in the middle of the field 　24　the other pilots on the ground shouted happily． “How silly I am!”he said．“I 　25　that the trees have grown since yesterday!”