请大家安静一下，老师要说话了。

Qǐng dàjiā ānjìng yíxià, lǎoshī yào shuōhuà le.

Everyone, please be quiet; the teacher is going to speak.

图书馆里很安静。

Túshūguǎn lǐ hěn ānjìng.

It is very quiet in the library.

我喜欢在安静的房间里学习。

Wǒ xǐhuān zài ānjìng de fángjiān lǐ xuéxí.

I like to study in a quiet room.