It was the first time a national political convention was held that far west.

VOA: special.2009.05.07

Convention, OK, this negative sign is just a pure convention. You just got to use it all the time. If you use an old textbook, written when I was taking thermodynamics, they have the opposite convention, and it's very confusing. But now we've all agreed on this convention, and work is going to be with the negative sign here.

系统对外界做功的符号为负,这就是我们,在本课中的规定，纯粹出于统一符号的需要，有些教科书中，可能会使用相反的符号规定,注意不要混淆了，这门课上,我们将一直使用。

麻省理工公开课 - 热力学与动力学课程节选

The convention sets out for the first time the obligations of both African states and armed rebel groups to prevent displacement and to provide basic rights for those who are uprooted by wars and natural disasters.

VOA: standard.2009.10.23

With the adoption of the Convention, she notes the international community unanimously recognized for the first time in history that children are not simply the property of their parents or guardians, but are in charge of their own destiny.

VOA: standard.2009.10.08