对这种图形应该分两步描述：
第一步：把同一个时间点的不同颜色的Bar看成一个整体，指出总量的变化趋势和最高最低值。
第二步：把单一颜色的element 独立出来，比较变化趋势。如果某个element的趋势是一致的，那么可以看成一条线，省略中间的数值，描述始末值即可。
若数值太大（如上图），可用倍数关系来表达数值间的关系。
(1) This bar chart shows the cereal production in Sub-Saharan African from 1969 to 2011.
(2) Generally, the total production increased significantly from just more than 40million tons to over 110 million tons.
(3) Maize and products were the major production, which almost tripled over the period from about 16 million tons to 58 million tons (or almost 20 to 60 million tons).
(4) Both wheat and Rice had much smaller outputs, but still experienced obvious increases.
(5) Other cereals made up 30 -40 percent of output over the period, and the output doubled from approximately 20 to 40 million tons.
这种图形是在40秒之内是不可能仔细描述的，只要讲出大趋势和变化最大的地方就可以了。有几点需要注意：
1.应使用的地理方面的专有名词来描述，如 equator，latitude, North/South Hemisphere, Atlantic, Antarctic, Africa等；
2.用东南西北指示方位，而不用上下左右；
3.通过对比来描述，对比的方面可以是
a. 赤道、低纬度地区和南北半球中高纬度地区 (Equatorial area/low latitude area VS mid/high latitude area)
b. 陆地和海洋 (continent and ocean)
c. 南半球和北半球 (South Hemisphere VS North Hemisphere)
d. 大陆东西岸。
(1) This map shows the land and ocean temperature departure from average in Feb 2016, based on the period of 1981 to 2010.
(2) For land area, Europe, northwest Asia and Alaska experience the most significant increase in temperature to almost 5 degrees, while most areas in the east part of Asia, especially China, experience considerable decreases form 1-3 degrees.
(3) For ocean area, the majority of the low latitude ocean areas has no change or slight temperatureincreases, while the ocean areas closed to the two poles experience decreases from 1 to 4 degrees.
PTE考核过的题目里已经有多个关于非洲的数据。不难发现，由于非洲地理环境特殊，大部分图形都有南北趋势相同，中间不同的特点。考试时可从南北向中间描述。同时也需要对东南面的小岛进行简单描述，可以用小岛本身的名字Madagascar也可以用small island 来指代。
(1)This is a map of African continent with climate zones and major rivers.
(2)There are 6 types of climate: Equatorial, Intrazonal, Subequatorial, Subtropical, Temperate and Tropical.
(3)Most areas in the North (Sahara Desert) and the South have tropical climate, while the central area of Africa and the island on the right (Madagascar) mainly have subequatorial climate.
(4)Interestingly, Equatorial climate only exists in the equatorial areas to the west of the Nile River.
