Since the 1930's aircraft manufactures have tried to build airplanes with frictionless wings ,shaped so smoothly and perfectly that the air passing over them would not become turbulent . A wings , shaped so smoothly and perfectly B wings , wings so smooth and so perfectly shaped C wings that are shaped so smooth and perfect D wings ,shaped in such a smooth and perfect manner E wings, wings having been shaped smoothly and perfectly so 答案为什么 是b啊?
[此贴子已经被作者于2007-3-2 16:43:22编辑过] |