第17题: [单项选择]He didn't ______ and so he failed the examination. A. work enough hard B. hard work enough C. hard enough work D. work hard enough 参考答案:D 答案解析:句法辨析题。enough修饰形容词,常放在形容词之后,如old enough;修饰名词时,通常放在名词之前,如enough food。故D为正确答案。句意:他没有充分地努力学习,所以在考试中失败了。