President Obama said working to fight climate change was a top goal of his administration.

VOA: special.2009.11.13

Whether you take the elevator to the top of the Hancock Tower or whether you walk up the stairs, the change in gravitational potential is identical.

不管你是乘电梯,去大厦的顶层,或者是步行，重力势能的变化是相同的。

麻省理工公开课 - 固态化学导论课程节选

World leaders of the top 20 economies are expected to discuss climate change during talks on the global economic downturn next month in London.

VOA: standard.2009.03.12

Yvo de Boer,the U.N.'s top climate change official, told delegates there was still time to break deadlocks, but he said countries that could be more ambitious should act now.

VOA: standard.2009.09.28

Most of the data comes from the industrialized world. Not surprisingly, burning fossil fuels for transportation and electrical generation top the list for their contributions to climate change, acid rain and toxic pollution.

VOA: standard.2010.06.04