我最近在看一本关于如何保持愉快的书。

Wǒ zuìjìn zài kàn yì běn guānyú rúhé bǎochí yúkuài de shū.

Recently I've been reading a book on how to stay happy.

你有什么保持年轻的方法？

Nǐ yǒu shénme bǎochí niánqīng de fāngfǎ?

What methods do you have for preserving your youth?

请保持安静，考试马上就要开始了。

Qǐng bǎochí ānjìng, kǎoshì mǎshàng jiù yào kāishǐ le.

Please keep quiet; the exam is about to start.