练习材料：
任务配置：L0+L1+L4
知识笔记：
2. 音标（L1)
中元音回顾：[ə][ɜː][ʌ] 所谓中元音，是指舌中部用力，而三者的区别在于口型，是否咧嘴，开口大小，是否紧张用力。
课中的单词：
[ə]: versus the police Christmas circus owner a children's Father accompanied honour elephant allow policeman approached along agreed policemen difficult amused afterwards arrest
[ɜː]: versus circus girls were
[ʌ]: Jumbo some up accompanied once but
练习感悟：
第二轮，还是很有必要的，查漏补缺啊！
