a long shot gamble的用法和样例：
- It's a long shot but I think John must have stolen the bike.
- It's a long shot, but I should say she's about forty.
- Looking for her in the library was a long shot; I had no idea where she was.
- Tom decided to put his money on a long shot.
- No. 6 gave a long shot, but missed the goal.
- Looking for her in the library was a long shot.