试题题干
Fill in each of the following blanks with a word or an expression.
In English ,all the back vowels except [a:] are 
vowels.
参考答案
试题解析
In English ,all the back vowels except [a:] are rounded vowels. 在英语中，除了[a:]之外所有的后元音都是圆唇音。
Fill in each of the following blanks with a word or an expression.
In English ,all the back vowels except [a:] are vowels.
In English ,all the back vowels except [a:] are rounded vowels. 在英语中，除了[a:]之外所有的后元音都是圆唇音。