汉语的声调在音节中是非常重要的部分，声音的音高变化将导致意义的变化，汉语拼音中一共有五种声调。我们用四个不同的声调符号来表示第一到第四声，没有声调符号的音节为轻声。声调符号一般标注在音节中的主要元音上。
    In Chinese language, tone is a very important part in a syllable. The changes of pitch cause changes of meanings. In Chinese Pinyin, there are 5 tones. We use 4 different tone symbols to represent the first to the fourth tones, and syllables without tone symbols are of neutral tone. Tone symbols are often marked on the main vowel of a syllable.
    以a为例：
    Take a for example :