adj.困难的，固执的，难以相处的

The mathematical problem proved to be quite difficult for the students to solve.
这个数学问题对学生来说确实很难解决。
The negotiations between the two countries were marked by numerous difficulties.
两国之间的谈判充满了重重困难。
She found it physically and emotionally challenging to adapt to her new job.
她发现适应新工作在身体和情感上都很有挑战性。
The intricate painting required a great deal of skill and patience, making it a difficult task for the artist.
这幅复杂的画作需要很高的技艺和耐心，对画家来说是一项艰巨的任务。
Despite his wealth, he still had financial difficulties managing his extravagant lifestyle.
尽管他很富有，但仍然难以维持他奢侈的生活方式。
The mountain hike was so strenuous that it posed a real physical challenge for the hikers.
这次山地徒步旅行非常艰难，对徒步者来说是一大体力挑战。
His illness made everyday tasks seem incredibly difficult for him.
他的疾病使他觉得日常任务变得极其困难。
The teacher had to devise a difficult but effective lesson plan to engage the advanced students.
老师必须设计一个既具有挑战性又有效的课程计划来吸引高年级学生。
The project manager found it hard to balance the tight deadline with the complex requirements.
项目经理发现很难在紧迫的截止日期与复杂的需求之间取得平衡。
After years of practice, she finally mastered the difficult dance routine.
经过多年的练习，她终于掌握了这个复杂的舞蹈动作。