The charts show pollutants entering a particular area of ocean in 1997 and in 2007
本文是一篇动态饼图，难度适中，六组数据可以分成两类，一类上升一类下降，因此我们可以按照趋势变化来分段，上升的三个污染来源写一段，下降的污染来源写一段。同时，要注意比较这六种污染来源中，哪一种是主要污染物，可以发现，无论是1997年，还是2007年都是pollutants from air最多，这个最大值需要强调。在比较的细节处理中，大家要注意，虽然分成上升下降两大类，但各个污染因素上升或下降的幅度并不一样，这一点也需要写到，比如同是上升，pollutants from the air上升的幅度就很小，而offshore oil上升的幅度比较大，需要通过单词或句式的变化体现出这两者之间的差异。
The two pie charts provide information about different kinds of pollutants which entered a particular area of ocean from 1997 to 2007.
We can see that this particular area of ocean was mainly polluted by the pollutants from air. And while the percentages of wastes from marine transport, industry and farm declined, the figures for other sources experienced different extent of increase.
The percentage of contaminant from air accounted for the largest amount in both years, increasing slightly from 30% in 1997 to 33% in 2007. The figures for domestic sewage and offshore oil grew dramatically from 18% to 32%， and 5% to 15% respectively in this period.
In 1997, Marine transport waste represented 22% of the total pollutants and the proportion of contaminant coming from industrial waste and farm waste was 17% and 4% respectively. However, by 2007, the figures for all of these three kinds of waste dropped to 8%, 10% and 2% respectively.