题目内容

蒸出的粗乙酸乙酯中主要有哪些杂质?如何除去?

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The motor car brings more ________ __________ than it promises to solve.

The aircraft creates a ________ _______ for time-consuming ________ that we never dreamed of.

The _______ machine, contrary to our expectations, __________ the hours spent on washing and _______.

Instead of making our lives easier, __________ goes so far as to _______ extra ______ into our _______ time.

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