你该不会是西班牙人吧？

You're not Spanish ___by ___any ___chance, are you?

你碰巧看到我的日记了吗？

Have you ___by ___any ___chance seen my diary?

请问您是否恰好有一份研究报告的副本？

Would you ___by ___any ___chance have a copy of the research report?