王海芳的回答：

1.如果一定要表明是很多人，可以用：Thank you all (谢谢你们所有人） 2.还可以：thanks to all of you. Thank you, everyone/everybody 3.Thanks to all the people contributed (谢谢所有做出贡献的人） you既是单数，也是复数，所以谢谢你们也可以是Thank you.

手捧阳光的回答：

thanks for your concerning/care! i'd appreciate for your concerning!