从小妈妈就教我必须要遵守承诺。

Cóngxiǎo māma jiù jiāo wǒ bìxū yào zūnshǒu chéngnuò.

From when I was young, my mother taught me I must keep my promises.

你必须把药吃完才会好。

Nǐ bìxū bǎ yào chīwán cái huì hǎo.

You must finish the medicine to recover.

这个決定我必须要认真考虑一下。

Zhège juédìng wǒ bìxū yào rènzhēn kǎolǜ yíxià.

I must seriously consider this decision.