请求合作应该怎么说英语

To request collaboration, you could say:
"I was wondering if you would be interested in collaborating on a project together. I think our skills and expertise would complement each other well, and I believe we could achieve great results as a team."
Alternatively, you could say:
"I have an idea for a project that I think would be a great fit for both of our skills and expertise. I would love to collaborate with you on it if you're interested."
It's important to clearly state your purpose and the potential benefits of the collaboration, and to be respectful and professional in your request.