The immune system loses its ability to tell the difference between foreign materials and its own cells.

VOA: special.2010.06.15

It has the function, in other words, of negating its own meaning in another semiotic system, in this case the semiotic system of the stoplight.

也就是说，他有这样那样的功能，在不同语义系统中表示的甚至完全相反，就像红灯表示的这些不同含义一样。

耶鲁公开课 - 文学理论导论课程节选

Yet,in some ways,the system has been a victim of its own success.

VOA: special.2010.01.11

And if we want this, then we have to make sure that Afghanistan has its own security infrastructure, that that system is there and we want to help build it,".

VOA: standard.2009.11.09