上课的时候不要大声讲话。

Shàngkè de shíhou búyào dàshēng jiǎnghuà.

Don't speak loudly during class.

他们在外面小声讲话。

Tāmen zài wàimiàn xiǎoshēng jiǎnghuà.

They are speaking quietly outside.

请大家安静，听老师讲话。

Qǐng dàjiā ānjìng, tīng lǎoshī jiǎnghuà.

Everyone, please be quiet and listen to the teacher speak.