What is a diphthong?

/aɪ/ is a rising diphthong. ( )

The first vowel of a diphthong is as long as the second vowel.

Which word with the diphthong(双元音) is different?

Which is NOT a rising diphthong?（ ） A: ei B: ai C: au D: a:

Which one of the following diphthongs is not closing diphthong. A: /eɪ/ B: /aʊ/ C: /ɔɪ/ D: /ɪə/

There are two types of vowels. One is pure vowel and the other is diphthong. A: 正确 B: 错误

中国大学MOOC: There are two types of vowels. One is pure vowel and the other is diphthong.

According to the tongue movements, [ aʊ] is a( )diphthong. A: centering B: falling C: opening D: rising

According to the tongue movements, [aʊ] is a（ ）diphthong. A: centering B: falling C: rising D: opening