就我的记忆来说……

As far as I can remember,...

What's John's last name? (约翰姓什么来着?)

As far as I can remember, it begins with M. (就我的记忆来说，它的第一个字母是M。)

To the best of my memory,...

As far as I know,... (就我所知……)

If my memory serves me right,... (如果我没记错的话，……)

以牙还牙，针锋相对。

Tit for tat.

John kicked me, so I gave him tit for tat.(约翰踢我，所以我以牙还牙。)

这是我为什么在这儿的原因。

That's what I'm here for.

What are you studying at Harvard? (你在哈佛大学学什么?)

Economics. That's what I'm here for. (学经济，这就是我为什么在这儿学习的原因。)

2+3等于5。

Two and three is five.

Two plus three is five.

Two and three makes five.

Two and three equals five.

我们有天壤之别。

We're as different as night and day.

We're completely different. (我们俩完全不同。)

We have nothing in common. (我们没有任何共同点。)