一白遮三丑

A white complexion is powerful enough to hide seven faults.

一知半解

A little knowledge is a dangerous thing.

一心一意

John is a person who always works with undivided attention.

一丘之貉

These people are cut from the same cloth./are tarred with the samebrush.

一目了然

His words just leapt to the eye. Do you need me to explain it?

一帆风顺

His business has gone off without a hitch.

一刻千金

You have to make good use of time. After all, every time counts.

一事无成

I am happy to know that all have ended in smoke about him.

一败涂地

The outcome of the election just bit the dust.

一针见血

His comment on the current affairs always hits the right nail on the head.