if
uk
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/ɪf/us
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/ɪf/ A2 conjunction used to say that a particular thing can or will happen only after something else happens or becomes true: I'll pay you double if you get the work finished by Friday. 如果你周五前完工，我付你双倍的报酬。
provided (that)
uk
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/prəˈvaɪ.dɪd ðət/us
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/prəˈvaɪ.dɪd ðət/ B2 conjunction if, or only if: He's welcome to come along, provided that he behaves himself. 他只要守规矩就欢迎他来。
suppose
uk
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/səˈpəʊz/us
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/səˈpoʊz/ C1 conjunction used at the beginning of a sentence or clause to mean 'what would happen if': Suppose we miss the train - what will we do then? 假设我们错过了火车——那我们该怎么办?
as/so long as
B1 phrase used to say that something must happen before something else can happen: I can come as long as I can leave by 4.00. 只要我能在4点钟之前出发，我就能来。
如果不是
if not
A2 phrase used to say what the situation will be if something does not happen: I hope to see you there but, if not, I'll call you. 我希望在那里能见到你，如果没有的话，我会给你打电话的。
如果不行
failing
uk
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/ˈfeɪ.lɪŋ/us
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/ˈfeɪ.lɪŋ/ preposition if that is not possible: Buy her some flowers, or failing that, just send her a card. 给她买一些花吧，实在不行，就寄一张卡去。
如果发生最糟的情况
if the worst comes to the worst
phrase UK if the situation develops in the most serious or unpleasant way: We should be in when you arrive, but if the worst comes to the worst, the neighbours have a spare key and will let you into the house. 你到的时候我们应该在家，万一不在，邻居家还有一把备用钥匙，能让你进屋。
如果改造成功
diversionary
uk
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/daɪˈvɜː.ʃən.ər.i/us
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/dɪˈvɝː.ʃən.er.i/ adjective dealing with someone, for example someone who has committed a crime, by giving them special treatment, rather than by sending them to prison, etc. The money went to the district attorney's office to pay for a diversionary scheme designed to reduce the prison population. 这笔拨款由司法区的联邦检察官用于资助转化性培训项目，以减少入狱犯人的数量。
如果计划均告失败
if all else fails
phrase if none of our plans succeed: If all else fails, we can always stay in and watch TV. 如果其他的都行不通，我们总是可以呆在家里看电视。
如果警察有理由认为某人持有毒品
stop and search
uk
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/ˌstɒp ən ˈsɜːtʃ/us
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/ˌstɑːp ən ˈsɜ˞ːtʃ/ noun mainly UK the power given to the police to search someone if they have a good reason to believe they are carrying drugs, a weapon, or stolen property, or an occasion when someone is searched: He wants to ramp up police stop and search in London in a bid to stop knife crime. 他想在伦敦加大警察截停及搜查的规模，以期杜绝持刀伤人案。
如果那种情况发生
in that event
phrase if that happens: There's a possibility of my flight being delayed. In that event I'll phone to let you know. 我乘坐的班机可能会晚点，如果是那样我会打电话通知你。
如果你不介意我说
if you don't mind me saying/asking
phrase used in order to be more polite when you say something that could slightly upset, annoy, or embarrass someone: If you don't mind me saying (so), I think the soup needs a little more salt. 如果你不介意的话，我认为汤里需要多加点盐。
如果你明白我的意思
if you take my meaning
phrase UK used to say that you have left out information or your opinion from what you have just said, but that you expect the person listening still to understand it: Let's just say we had "problems", if you take my meaning. 我们就姑且说我们遇到了“问题”吧，如果你明白我所指的是什么的话。
如果你愿意那样说的话
if you will
phrase used to say that a particular expression is one way of saying something, especially to suggest that some people may not choose to say it that way: I did very well in school , with a "genius IQ" if you will. 我在学校成绩很好，有“天才智商”，如果你愿意那样说的话。
如果你愿意
if you like
phrase UK used for asking if someone agrees with a suggestion: We can leave now if you like. 如果你愿意，我们可以现在就走。
如果是那样的话
in that event
phrase if that happens: There's a possibility of my flight being delayed. In that event I'll phone to let you know. 我乘坐的班机可能会晚点，如果是那样我会打电话通知你。
如果是那样
in that case
B2 phrase because of the mentioned situation: There's no coffee left? In that case I'll have tea. 没咖啡了？既然如此，我就喝茶吧。
如果是天意
God willing
phrase used to say you hope everything happens in the way you want: We'll be there tomorrow, God willing! 要是一切顺利的话，我们明天就会到那儿！
如果我没记错的话
to the best of my recollection
phrase formal from what my memory tells me: To the best of my recollection I have never seen her before. 如果我没记错的话，我以前从来没有见过她。
if my memory serves me right
phrase if I remember correctly: I think he was called Blake, if my memory serves me right. 如果我没记错的话，他叫布赖克。
如果我没说错的话
correct me if I'm wrong but...
phrase said as a polite and slightly formal way of disagreeing with someone: Correct me if I'm wrong, but I think we arranged the meeting for the 12 December. 如果我没记错的话，我想我们是把会议安排在了12月12日。
如果我是你的话
if I were you
B1 phrase used when you give someone advice: If I were you, I'd probably go. 如果我是你，我可能会去。
如果我是你
if I were in your shoes
phrase informal used when you want to tell someone what you would do in their situation: If I were in your shoes, I think I'd write to her rather than try to explain over the phone. 如果我是你，我想我会给她写信而不是在电话里向她解释。
如果我知道
I'll be hanged if I know
phrase UK old-fashioned informal used to say that you certainly do not know
如果一切顺利
all things being equal
phrase if everything happens as expected: All things being equal, I'll be at home on Tuesday. 如果一切顺利，我星期二就能回家。
如果一切照常
all things being equal
phrase if everything happens as expected: All things being equal, I'll be at home on Tuesday. 如果一切顺利，我星期二就能回家。
如果有必要的话
if need be
phrase if it is necessary: If need be, we can take two cars. 如果有必要的话，我们可以要两辆车。
如果再抱怨就别干了
if you can't stand the heat, get out of the kitchen
phrase saying used as a way to tell someone that they should either stop complaining about a difficult or unpleasant activity, or stop doing it
如果最坏的事情发生
if the worst comes to the worst
phrase UK if the situation develops in the most serious or unpleasant way: We should be in when you arrive, but if the worst comes to the worst, the neighbours have a spare key and will let you into the house. 你到的时候我们应该在家，万一不在，邻居家还有一把备用钥匙，能让你进屋。