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- He may succeed,but I don't know for certain. 他也许能成功，但我不敢肯定。
- I don't know for certain when he will come. 我无法确定他什么时候回来。
- He may succeed, but I don't know for certain. 他也许能成功，但我不敢肯定。
- I do not know why acids eat in metals. 我不知道酸腐蚀金属的原因。
- I do not know whom he has in mind for the job. 我不知道他想让谁来做这项工作。
- I do not know whom he have in mind for the job. 我不知道他想让谁来做这项工作。
- I do not know the English equivalent for the word. 我不知道这个字的英语相当语为何。
- I fear I do not know the answer to that. 我恐怕回答不出那个问题。
- I do not know that you'd fallen ill for days. 我不知道你病了好几天了。
- I do not know what is says,for I cannot resd. 我不知道它说些什么，因为我不识字。
- Gee! I do not know this guy cry so much when he's drink. 哇啊！我不知道这老兄一喝酒，就会嚎啕大哭。
- I didn't know for certain where I should go at that time. 那时，我的确不知道该到哪儿去。
- What others think I do not know; I can only speak for myself. 别人怎么想我不知道，我只能代表自己讲话。
- I do not know how to spell the word " tulip ". 我不知怎么拼"郁金香"这个词。
- I do not know,but he will certainly be back for lunch. 我不清楚，不过他肯定会回来吃午饭的。
- I am sorry I do not know anything about that. 很抱歉这事我一点儿也不知道。
- I do not know how I can thank you enough. 真不知道怎样感谢您才好。
- I do not know how to say it in English. 我不知道怎样用英语来讲这句话。
- I do not know where to begin counting them. 我不知道该从哪里着手数起。
- I did not know ( that ) you'd fallen ill for days. 我不知道你病了好几天了。
