Dear Sir，
We have a pleasant interview last month, and your kindness left me a deep impression.Thank you for your time.
Since then,however,I haven't heard anything from you and I'm beginning to worry about that.I'd like to know whether you have made your decision or not.If you don't think I'm qualified enough,I hope you would be kind enough to keep my resume on file and give me an opportunity next time.
Your timely response appreciated.