Let's get this straight. *“我得先把话说清楚”、 “这点我可告诉你” 这样引起对方的注意力之后，表达自己的意见才有效果。
Let's get this straight, I'm the boss. (我得先说清楚，我是老板。)
Yes, sir. (是的，先生。)
我是不会做那种事儿的。
I would not do that.
I would not do that. (我是不会做那种事儿的。)
I believe you. (我相信你。)
I wouldn't do that.
I wouldn't ever do that. (我是绝对不会做那种事儿的。)
I'm not the kind of person who would do that. (我不是做那种事的人。)
还有更厉害的呢。
You ain't seen nothing yet. *按正确的语法关系来说，应该是You haven't seen anything yet.直译是“你还有很多没看到呢”。
A) Shibuya is very crowded. (涉谷人多得要命。)
B) You ain't seen nothing yet. You should see Shinjuku. (你没看到更厉害的呢，你去新宿看看。)*美国朋友A来到日本。
不要画蛇添足了。
Let's leave well enough alone. *直译是“这样就很好了，保持别动了”。表示“这种状态就很好，所以如果再修改的话就会画蛇添足”。
One more hand. (再玩一次吧。)
Let's leave well enough alone. (这样就行了，到此为止吧!)*玩扑克游戏时。
Let's quit while we're ahead.
Let's not try to improve the results. *这种表达方式不常使用。
肯定是我的幻觉。
It must be my imagination. *imagination “空想”、“想像”。
从长远来看……
In the long run,...
Tax cuts are a good idea. (减税是个好主意。)
But, in the long run, it's not good for the country. (但从长远来看，对国家没有什么好处。)
●叙述、询问理由
为什么?
Why?
I forgot to lock the door. (我忘了锁门了。)
Why? (为什么?)
为什么?
How come? *比why?还要口语。
I didn't like the movie. (我不喜欢那部电影。)
How come? (为什么?)
你怎么会那么想呢?
What makes you think that?
I think she's in love with you. (我想她爱上你了。)
What makes you think that? (你怎么会那么想呢?)
Why do you say that?
Why do you think that?
告诉我为什么。
Tell me why.
What's the reason? (理由是什么?)
是怎么发生的?
How did it happen?
My car broke down. (我的汽车出故障了。)
How did it happen? (是怎么回事?)
How did that happen?
你干吗要去做这种事呢?
What are you doing this for? *当不明白对方为什么要做毫无理由的事情的时候使用。
Why are you doing this?
What's the reason you're doing this?
Why are you doing something like this? (你干吗要干这样的事呢?)
你为什么干那样的事呢?
Why did you do that?
Why did you do that? (你为什么干那样的事呢?)
I didn't know I wasn't supposed to. (我不知道不能这样做。)
What made you do that?
Why did you do something like that?
How could you?
How could you do that?
是什么原因呢?
What causes it? *cause“成为……的原因”、“引起”。
The river is getting dirty. (那条河越来越脏。)
What causes it? (为什么会这样呢?)
What causes it? (是什么原因?)
Air pollution. (由于空气污染。)
What is it caused by?
请给我解释一下。
Explain it to me.
You'd better start explaining.
为什么不行?
Why not? *在被对方否定时，反驳对方“为什么不行?”，还含有“当然可以”、“同意”的意思。
You can't wear the red pants. (你不能穿那条红裤子。)
Why not? They're my favorite. (为什么不能?这是我最喜欢的裤子。)
Why can't I?
Is there a reason? (有理由吗?)
你怎么那么高兴?
What are you so happy about?
What are you so happy about? (你怎么那么高兴?)
It's a wonderful day. (今天是最棒的一天。)
You seem especially happy today. (你今天显得特别高兴。)
What makes you so happy? *更随意的说法。
为了什么?
What for?
I made this big box! (我做了个这么大的箱子。)
What for? (干什么用?)For what?
What is this for? (这个用来干嘛?)
为了谁?
For who?
I bought this gift today. (今天我买了一份礼物。)
For who? (给谁买的?)
Who is it for?
你旅行的目的是什么?
What's the purpose of your visit? *出境游时，边防检查官的问话。
What brought you here? (你为什么来这儿?)
没有理由不让做吧。
No reason not to.
Why do you want to do that? (你为什么想做那件事?)
No reason not to. (没有理由不让做吧。)
Why not?
What's wrong with it?
Why shouldn't I?
你怎么在这儿?
Why are you here? *根据说话方式的不同，有时会让对方听起来不礼貌。
我告诉你为什么……
I'll tell you why...
This is the reason why...
总之，是这么回事儿。
In brief, it's like this. *比较随便的说法，用在说出重点之前。虽然不是正式的说法，但可用于所有情况。
In short, it's like this.
In a word, it's like this.
To sum up, it's like this.
它的由来是这样的……
It started like this...
How did Edison make the light bulb? (爱迪生是怎样发明灯泡的呢?)
It started like this... (它的由来是这样的……)
This is its history...
This is the way it began...
原来如此!
That's why! *比较随便的说法。
Why doesn't it work? (为什么不动呢?)
You have to turn it on first. (你得先打开开关。)
Oh, that's why! (哦，是这样啊!)
所以……
That's why...
That's why I like her. (所以我喜欢她。)
I see. (我明白了。)
●指出错误
我觉得你错了。
I think you're mistaken.
I think you've been misled.
你错了。
You're wrong.
That man is Mr. Smith. (那位是史密斯先生。)
You're wrong. He's Mr. Sheehan. (你错了，他是希恩先生。)
You're incorrect.
那是谁的错呀?
Whose fault is that? *含有责备对方的语感。
Whose fault is it?
Who's to blame?
吃不着葡萄就说葡萄是酸的(还嘴硬!)
I think it's sour grapes. *sour grapes是意为“酸葡萄”、“不认输”的惯用表达方式。它来自有名的伊索寓言。“狐狸看到树上长满了诱人的葡萄，可是怎么也够不着时，就说那葡萄是酸的，算了吧。”狐狸嘴硬，但却不得不死心。
I think it's a case of sour grapes.
那随你的便。
That's up to you. *up to... 表示“随……的便”、“由……决定”。
Should I buy a red car or a blue car? (我是买红色的汽车还是买蓝的?)
That's up to you. (那就随便你喽。)
You choose.
You decide.
你没说到点儿上。
That's not the point.
He's poor because he's lazy. (他很穷是因为他很懒。)
That's not the point. (你没说到点儿上。)
That's not the issue.
That's not what I'm talking about.
对不起，那是我的。
Excuse me. That's mine. *当发现别人错拿走什么东西时使用。
That doesn't belong to you. (那不是你的。)
Excuse me, that's not yours. (对不起，那不是你的。)
I think that belongs to me. (我想那是我的。)