要是

zhè shì yào shi jiào tā zhī dào le yī dìng huì fā shēng zhēng chǎo

这事要是叫他知道了，一定会发生争吵。

Once he gets wind of this, there must be a quarrel.

yào shi bié rén wǒ cái bù guǎn ne

要是别人，我才不管呢。

If it had been somebody else, I wouldn't have bothered myself.

yào shi fā shēng huǒ zāi jiù gǎn kuài àn líng

要是发生火灾，就赶快按铃。

In case of fire, touch the bell.

yào shi xiǎo lǐ zài zhè r tā jiù zhī dào gāi zěn me qù zuò

要是小李在这儿，他就知道该怎么去做。

If Xiao Li was here, he would know what to do.