According to__________ , vowels can be classified into three groups: front, central, and back.
A.the openness of the mouth B.the shape of the lips C.the position of the tongue D.the length of the vowels正确答案C
According to__________ , vowels can be classified into three groups: front, central, and back.
A.the openness of the mouth B.the shape of the lips C.the position of the tongue D.the length of the vowels正确答案C
