The gravity on mars is only about three-eighths of that on
问题描述：
The gravity on mars is only about three-eighths of that on
The gravity on mars is only about three-eighths of that on earth 和 I think two thirds of tne materials I listened to at the beginning of the exam are easy.句一的 three-eighths 有连接符 但句二的 “two thirds ” 没有连接符?
答
其实加不加-都可以,现代英语一般不加-