Did you mark the right position?

The four tones of Chinese PinYin is the key and difficult point in Chinese pronunciation. Do you know where are the four tone marks? Try to mark the following words first.
1. yan (3).      2.  ge (1)      3. mei (2).     4. sheng (3)     5. jiu (4)
Did you mark the right position? (the answers please see the end of the article)
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Now let's understand the rules of PinYin together.
Rules 1:  When a syllable contains a single vowel only, the tone-mark is placed above the vowel.
    e.g.              ā    ō   é   ī   ú   ǚ
                        ān  èn  ér  ǐn  ùn  èng  āng

Rules 2:  When a syllable contains or more vowels, the tone-mark should be placed above the main vowel (the one pronounced mone loudly and clearly ),  
    e.g.             āi   āo  ōu   iè    üè

Rules 3: When a tone mark above the vowel "i", the dot over it sould be omitted.
    e.g.             mí    jǐng

Rules 4:  When " iu " or " ui " comes, the tone-mark should be placed above the terminal vowel,
    e.g.             liú    guī

 Answers:  yǎn（眼）  gē（歌） méi（没）  shěng（省）  jiù（旧）