third 第三 3rd fourth 第四 4th fifth 第五 5th sixth 第六 6th seventh 第七 7th eighth 第八 后面简写都一样的 ninth 第九 tenth 第十 eleventh 第十一 twelfth 第十二 thirteenth 第十三 fourteenth 第十四 fifteenth 第十五 sixteenth 第十六 seventeenth 第十七 eighteenth 第十八 nineteenth 第十九 twentieth ... 4th是序数词fourth的阿拉伯数字形式，表示第四的意思。 任何语言里都有序数词，俄语的序数词是由基数词的第二格形式的词干加上形容词词尾构成。 Previous industrial revolutions liberated humankind from animal power, made mass production possible and brought digital capabilities to billions of people. This Fourth Industrial Revolution is, however, fundamentally different. It is characterized by a range of new technologies that are fusing the physical, digital and biological worlds, impacting all disciplines, economies and industries, and even challenging ideas about what it means to be human. 1st,2nd,3rd,4th,5th,6th,7th,8th,9th,10th,11th,12th这些是什么意思啊这些是序数词。 序数词是指表示顺序的词，是数词的一种，主要在英语语法中讲到，英语上数词分为两大类：基数词和序数词。
