Introduction

Tone marks: when there is a single vowel, put the tone mark on it. When there are two or three vowels, follow the order of “a, o, e, i, u, ü”. For example, the tone mark should be put above “a” in “tiao”. When “i” and “u” are together, the tone mark is put above whichever comes last. For example, “diū” and “huī”.