第27题: [单项选择]Helen did not go to bed early last night because she had to ______ for today's English test. A. stay later B. sat late C. stay up D. study later 参考答案:C 答案解析:[精解] 动词短语题。stay later意为呆晚一点,不一定熬夜;没有sit late这一短语;stay up熬夜之意;没有study later这一短语;因此[C]为正确的选项。