n.誓言,郑重宣布 vt.& vi.起誓，发誓,郑重宣告
The vowel in words like "my" and "thigh" is not very difficult.
单词my和thigh中的元音并不难发。
Each language has a different vowel system.
每种语言都有不同的元音系统。
A long vowel is a long sound as in the word'shoe ".
长元音即如“shoe ” 一词中的长音.