I followed your instructions to the letter.

我是严格遵照你的指示办的。

They insist on sticking to the letter of the law.

他们坚持严守法律的字面意义。

I put a lighted match to the letter and watched it burn.

我划了根火柴点着了那封信，然后看着它燃烧。

We are going to execute our campaign plan to the letter.

我们将严格执行我们的竞选方案。

I'm writing in response to the letter you wrote to me yesterday.

昨天收到你的来信，写此信作为回复。