---We are informed that the Weifang International Kite Festival starts at 7:00.

---Oh, I didn't expect it was so early! I ________ to go out for dinner with my friends first.

A．was planning

B．am planning

C．have been planning

D．have planned

在 X.509标准中，数字证书一般不包含（ ）。

A．版本号

B．序列号

C．有效期

D．密钥