拼合规则

In the common "i" : When preceded by no initial,the finals are written as yi,ya,ye,yao,you,yan,yin,yang,ying or yong.

In the common "u" : When preceded by no initial, the finals are writtern as wu, wa, wo, wai, wei, wan, wen, wang or weng.

In the common "ü" : When preceded by no initial, the finals are writtern as yu, yue, yuan or yun, without two dots above  "ü".

In the common "ü" : When going with "j","q", or "x" the final "ü" is written without two dots above such as in ju, qu,xu;juan, quan, xuan; jue, que, xue; jun, qun, xun. But the two dots remain unchanged when "ü" is written with "n" adn "l".

The initials "j", "q", and "x" are never used with "ü".
When preceded by an initial, "iou","uei" and "uen" are reduced to "iu", "ui" and "un" in their respective writing.