1、30的英语：thirty，英 [?θ??ti] 美 [?θ??rti]。
2、By this time he was thirty。到那时他30岁了。
3、There were thirty students present,reckoning without the girlstudents。不算女生，有三十个学生出席。
4、His words refreshed my memory that he remained a bachelor at the age of thirty。他的话使我回想起他三十岁时还是个光棍。