信封

我撕开了信封。

Wǒ sī kāi le xìn fēng.

I ripped the envelope open.

我在信封上写错了地址。

Wǒ zài xìn fēng shàng xiě cuò le dì zhǐ.

I wrote the wrong address on the envelope.

我忘记在信封上贴邮票了。

Wǒ wàng jì zài xìn fēng shàng tiē yóu piào le.

I forgot to put a stamp on the envelope.