what's the definition of vowel(s)?
查看答案
The English pure vowels can be classified according to
A. the position of the lips.
B. the height of the raised part of the tongue.
C. the dgree of obstruction to the flow.
D. the part of the tongue raised.
/i/ is a much more tense sound than /i:/.
A. 对
B. 错
/e/ is a central vowel.
A. 对
B. 错
There are 20 pure vowels, in English.
A. 对
B. 错
微信支付 
支付宝支付