He says that in the Antarctic Peninsula, scientists estimate that climate change has caused temperatures to increase by two or three degrees Celsius over the past fifty years.

VOA: special.2009.06.03

The interesting thing is that through time, as political winds change, these taxes have changed and they've gone up to some very high levels in the past in the United States and other countries.

有趣的是在不同时期,如果政策方向有所转变,税率也会改变,在过去的美国和其他国家,税率曾经相当高

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Dr.Anond Snidvongs, who has studied climate change for more than a decade, has analyzed storm data over the past 60 years.

VOA: standard.2009.12.21

He says the new Obama war strategy, which also includes a major rehaul of civilian development projects, sounds like a hopeful change from the past.

VOA: standard.2009.06.15

continues to be a celebration of the profound change in this hemisphere as compared to many periods in the past when the hemisphere was marked by undemocratic governments.

VOA: standard.2009.04.15

The sea change in the approach towards dealing with the past has also opened the door for the exhumations,says Jose Suasnavar of the Foundation for Forensic Anthropology of Guatemala.

VOA: standard.2009.12.18

Indeed,volatile food prices, population growth, low agricultural productivity and the potentially devastating effects of climate change make it a particularly daunting challenge. The IFAD president says over the past 30 years, agricultural productivity in developing countries has been stagnant or in decline. He blames it on years of under-investment.

VOA: standard.2010.03.29