Change of tones in Chinese language

To learn Chinese and learn more news from China, please visit http://www.gurulu.com/en

The tone of a Chinese word sometimes changes when used in a sentence depending on the tone of the word that preceds or comes after it.

Rule 1:
If a 3rd tone is followed by a 3rd tone, the first 3rd tone becomes second tone.
e.g. 手表 古典 美好 理想

Rule 2:
If a 3rd tone is followed by any tone other than the 3rd tone (covered by rule 1) the 3rd tone changes to a "half 3rd tone." A "half 3rd tone" is one that falls, but does not rise.
e.g. 首先 祖国 广大 耳朵

Rule 3:
Rules concerning the word "不"
The word "不" is 4th tone, but when it is followed by another 4th tone, it becomes 2nd tone.
e.g. 不会 不但 不论 不必 不变 不是 不信 不料 不愧 不错
when 不 is between a verb and an adjective, it becomes neutral tone.
e.g. 好不好 行不行 看不清 打不开

Rule 4:
Rules concerning the word "一"
The word "一" is 1st tone when used as part of a number (一, 二, 三, ... 十一).
The word "一" is 4th tone when preceeding 1st, 2nd, or 3rd tones.
e.g. 一般 一端 一经 一边
一时 一群 一条 一团
一举 一早 一手 一体
The word "一" is 2nd tone when proceeding a 4th tone.
e.g. 一道 一次 一定 一致 一律 一晃 一动 一并 一刻 一路
The word "一" is neutral tone when it's between two reduplicated verbs.
e.g. 看一看 想一想 问一问 学一学