【简答题】什么是X.509方案,它是如何实现数字签名的?
【单选题】she showed me her new dress . 此句属于_______________。
【单选题】Our president made a(n) ____ speech at the opening ceremony of the sports meeting which encouraged the sportsmen greatly.
【单选题】— Did Tom's parents go to the meeting yesterday? — Yes, ____ of them did, but ____ spoke. [ ]
【单选题】为了实现看板管理,在使用看板时必须遵守( )条规则。