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2011-09-20 17:21:00   来源：作文地带    双击单词自动翻译

作文地带导读：First, add the two parallel vectors, A and B. Because they are parallel, this is a simple matter of straightforward addition: 9 + 3 = 12. So the vector A + B has a magnitude of 12 and points due north. Next, add A + B to C. Th