have a hand in
參與A:Are you having a hand in looking into the case?
A:你參與調查那件案子了嗎?
B:Yes.
B:是的。
A:How do you feel about it?
A:怎麼樣?
B:It's really a hard nut to crack, The probelm is that the crime was done without leaving any trace.
B:案子很棘手,問題是
犯罪分子未留下任何線索。