There are a few cases in Chinese where you have to change the pronunciation of a certain character.
There are three main tone change rules in Chinese YOU MUST KNOW!! These are…
不 usually pronouns as “bù.” But it can change to “bú” when it follows by a 4th tone word.
一 pronouns as “yī.” But it can change to “yí” or “yì.”
And if you see two third tone in a row, the pronunciation of the first word will change to the second tone.
See infographic for more detail!
Chinese Simplified Version