【问】 cannot but，cannot help but与cannot help在意义和用法上有什么区别?
 【答】 这三个短语在意义上基本相同，都表示“禁不住”、“不由得”、“不得不”、“不能不”的意思，但用法和语体有区别。cannot help之后跟动名词，是最规范的用法，因此最为常见(为所有的英语辞典所收纳)，并常见于标准英语考试中：
 1. I can’t help admiring the picture whenever I look at it.(EC)
 不管我什么时候看到这幅画，我都禁不住要赞赏它。
 2. She could not help feeling depressed.
 她不禁感到很沮丧。
 cannot but后面要跟不带to的不定式。这种用法不大规范。不少语言学家认为是个不好的用法。但是我们不时还是能见到这种用法：
 1. I cannot but admire your decision.
 我不能不赞赏你的决定。
 2. One's world outlook cannot but come through in what one says and does.一个人的世界观必然在其言行中表现出来。
 3. I cannot but admire the truth of your remarks，although they go against my interests.(LDCE)
 我不能不欣赏你的话的真实性，尽管它们违背我的利益。
 4. When the country calls you for help，you cannot but go. (DAI)
 当国家需要你的时候，你必须挺身而出。
 5. When a close friend dies，you cannot but feel sad.
 好朋友去世时，你一定会感到悲伤。
 cannot help but后面也要跟不带to的不定式。这种用法多见于非正式语体。语言学家们(如Hornby以及RWRT的作者们)认为它是合乎语言习惯的。而且托福试题也采用了这种句式，见cannot help but之托福试题(71.5)。
 1. You can't help but respect them.
 你禁不住会尊敬他们。
 2. When the streets are full of melting snow，you can't help but get your shoes wet.当街道满是融化的雪水时，你是不能不把鞋子弄湿的。
 3. The application of cold compresses cannot help but reduce the swelling.
 用冷敷法必定可以消肿。
 4. I couldn't help but remark about the poor service in the restaurant.
 我不得不对饭店极差的服务质量说几句。
 请做下面的英语试题：
 1. “If you’d been here ten minutes earlier，you could have seen the doctor.” “But Icouldn't help________ . Traffic was heavy. ”
 A. to be I B. being late
 C. that I am late D. lateness(TOEFL，74. 1;75. 11)
 2. My younger brother couldn't help________ when his toy car fell into the river.
 A. but to cry B. but crying
 C. to cry D. crying(EPT)
 3. “I know it isn't important but I can't help________ about it. ”
 A. but to think B. thinking
 C. think D. to think(攻读硕士学位研究生入学考试英语试题，80A)