今天我收到了一封挂号信。

Jīntiān wǒ shōudào le yì fēng guàhàoxìn.

Today I received a registered letter.

哇，今天诊所里等挂号看医生的人特别多。

Wa, jīntiān zhěnsuǒ lǐ děng guàhào kàn yīshēng de rén tèbié duō.

Wow, there are especially many people at the clinic today waiting to register to see the doctor.

重要信件寄挂号比较好。

Zhòngyào xìnjiàn jì guàhào bǐjiào hǎo.

It’s better to send important letters by registered mail.