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(a) Construct a double-stem-and-leaf plot for the life
span of the fruit flies using the stems 0{\star}⋆, 0{\cdot}⋅, 1{\star}⋆, 1{\cdot}⋅,
2{\star}⋆, 2{\cdot}⋅, and 3{\star}⋆ such that stems coded by the symbols
{\star}⋆ and {\cdot}⋅ are associated, respectively, with leaves 0
through 4 and 5 through 9.
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我必须在 R 中这样做，但我不能使用 stem.leaf.backback 或 stem.leaf 命令。我怎样才能做到这一点？