Have you decided, Mr. Brown?

布朗先生，你决定了吗?

I've thought it over, and I feel it will be a big mistake if I don't accept your proposal.

我己经反复考虑了，我觉得不接受你的建议是个大错误。

Great! Now let's sign the contract.

太好了!那我们签合同吧。

And I feel it will be a disaster if I accept it.

我觉得如果我接受它会是一场灾难。

proposal n.提议，建议;求婚
disaster n.灾难，大祸;彻底的失败
think over 仔细考虑，掂量