I can assure you of the reliability of the news.
I assure you my actions will correspond with my words.
He hastended to assure us that the press would not be informed. 急忙保证
availability 可用性 有效性
The availability of cheap long-term credit would help small business.
Before travelling we must ensure the availabilit of petrol and oil.
available 可用的 可获得的
Since 1978, the amount of money availability to buy books has fallen by 17%.
He is due to address a conference on human rights next week. 发表演说
The two foreign ministers did not address each other directly when they last met. 外交部长，没有直接语言交流
Mr.King sought to address those fears when he spoke at the meeting. 试图消除恐惧
the process or action of proving or showing something to be true, genuine, or valid. 所以 authentication 不能也有验证的意思。