习语：a hard nut
讲解：nut除了指“坚果”的意思，还可以指“难题、难事、难对付的人”。A hard nut源于短语a hard nut to crack或者是a tough nut to crack，表示“顽固不化的人”“无知无觉的人”“顽冥不化的人”。
英语情景对话：
A: Bob refused all his classmates' invitations.
Bob 拒绝了班上所有人的邀请。
B: I really couldn't understand him.
我真不明白他这个人。
A :He is surely a hard nut, nobody likes approaching him.
他真是个脑子不开窍的人，没人愿意接近他。
B: We’d better leave him alone.
我们最好也别惹他。
leave alone：不理睬，不干涉，置之不理，不打搅
He will leave alone things that might cause trouble; as he would say, “Let sleeping dogs lie.".
他从来不干招惹是非的事。他会说：“莫惹是非”。
Leave my books alone.
别动我的书。
Just buzz off and leave me alone.
走开, 让我清静一下!
