difficult与hard这两个形容词均有“困难”之意。
difficult比hard较为正式，侧重需要特别的能力、智力、判断力、技巧或勇气才能克服障碍。也可指深奥或抽象的难题。
- a difficult problem/choice/task/language
难题／艰难的选择／艰巨的任务／难学的语言 - It will be very difficult to prove that they are guilty.
证明他们有罪将非常困难。
hard : 含义广，通俗用词，与easy相对，泛指任何难理解，不好处理或不易做的事。
- He's a hard man to please.
他是个难以取悦的人。 - It's hard to say which of them is lying.
很难说他们当中哪个在说谎。 - It's hard being a single mother.
做单身母亲很艰难。 - Her handwriting is very hard to read.
她的字迹很难辨认。
