— What about having a picnic in Beibei Park this weekend?

— _______. I think it'll be interesting. [ ]

A. That's all right

B. Thank you

C. I hope not

D. I couldn't agree more

数字证书的作用是证明证书中列出的用户合法拥有证书中列出的（）

A． 私人密钥

B．加密密钥

C．解密密钥

D．公开密钥