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a cafeteria has a lunch special, consisting of soup or salad, a sandwich, coffee or tea, and a dessert. If the menu lists 3 soups, 2 salads, 8 sandwiches and 7 desserts, how many different lunches can you choose (Note: two lunches are different if they differ in any aspect A. 22 B. 280 C. 336 D. 560 E. 672 我选B. 老师说 有 or 用加法, 有and用乘法。 (2+3) * 5*7=280 这样想法对不对啊?老师讲完,没说答案,来CD上讨教一下 另外,这种题,是否如果题目中两个项目之间有逗号,就相当于用了单词and,就要用乘法啊? |
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