difficult problem
短语词组
- a difficult technical problem 一个难题
- difficult point problem 难点问题
- difficult technical problem 技术攻关
- difficult theoretical problem 理论难题
- solve the difficult maths problem 解决困难的数学题
- solve a difficult technical problem 攻克技术难关
- so the difficult technical problem 悬而未决的问题
- Joseph Needham 's difficult cultural problem 李约瑟文化难题
- big and difficult problem 老大难;老大难” 返回 difficult problem