Treasury Secretary Tim Geithner says the financial crisis developed in part because the existing system let some companies "shop for the weakest regulator."

VOA: special.2009.06.19

You could imagine a protein that's existing inside a cell at some level of abundance.

想像一下,在细胞中有一种大量存在的蛋白

耶鲁公开课 - 生物医学工程探索课程节选

Some gardeners prepare an area by removing the existing top soil and grass.

VOA: special.2009.07.07

However,Professor Cacioppo says existing research offers some possibilities.

VOA: special.2009.12.22