Word: 没关系 (méiguānxi)

他们知不知道都没关系。

Tāmen zhī bù zhīdào dōu méiguānxi.

It doesn't matter if they know or not.

别人怎么看都没关系。

Biéren zěnme kàn dōu méiguānxi.

It doesn't matter what other people think.

多少钱都没关系。

Duōshǎo qián dōu méiguānxi.

It doesn't matter how much it costs. (Probably best if you don't say this one too much.)

多长时间都没关系。

Duō cháng shíjiān dōu méiguānxi.

It doesn't matter how long it takes.

我用铅笔写没关系吧？

Wǒ yòng qiānbǐ xiě méiguānxi ba?

It doesn't matter if I use a pencil, right?

没关系。大家都是这样。

Méiguānxi. Dàjiā dōu shì zhèyàng.

It doesn't matter. Everyone does it.

这事跟我一点也没关系。

Zhè shì gēn wǒ yìdiǎn yě méiguānxi.

This issue has nothing to do with me.