单词：thickened underflow
浓密底流
单词：thickened underflow 相关文章
Lesson 37 All About A Penny 第37课 关于便士 When I was a little boy, pennies, and halfpennies, and farthings were made of pure copper. But copper is too soft a metal to stand the rubbing which coins get. So these old pennies soon became so smoo
发表于:2019-02-07 / 阅读(205) / 评论(0)
英国学生科学读本
英国学生科学读本