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。)