Mother told Tom to watch the milk until it boiled and then__off the gas. 为什么是 turn.不是turned

题目

Mother told Tom to watch the milk until it boiled and then__off the gas. 为什么是 turn.不是turned
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答案

这是tell sb to do A and do B 的结构 told 之后有两个不定式短语做宾补to watch the milk until it boiledto turn off the gas当两个不定式被并列连词and 等连起来时第二个不定式常省去to所以此空为动词原形&n...