Tone Change Rules in Mandarin Chinese
 
1.  THIRD TONE

     A third tone followed by another third tone changes to the second tone. If there are three or more third tones in a row, change every other third tone before the last.

 
     When followed by a first, second, fourth, or neutral tones, a third tone should change into a half third tone (that is, a tone that falls and does not rise).
 

2.  NEUTRAL TONE

     The neutral tone, when following the first, second and fourth tones is pronounced low. However, when following the third tone, it is pronounced high.

 
3.  NO and ONE

     BU (meaning "no") is pronounced in the fourth tone when it stands alone.

It is also pronounced in the fourth tone when it precedes a first, second, or third tone. However, it is pronounced in the second tone when it precedes a fourth tone.

 
     YI (meaning "one") is pronounced in the first tone when it stands alone.

It is pronounced in the fourth tone when it precedes a first, second, or third tone. However, it is pronounced in the second tone when it precedes a fourth tone.