句式一: 变化主体/图画中主体+趋势动词+副词+时间区间
Eg: The number of aged people over 65 increased significantly from1940-2000.
The number of aged people over 65 dropped slightly from 1960-1980.
The number of aged people over 65 fluctuated between 1 million and 1.2million from 1940-1950.
The number of aged people over 65 remained stable from 1930-1940.
句式二: There be + 形容词 + 表示趋势的名词 + in+ 变化的主体+ 时间区间
Eg: There was a significant increase in the number of aged people over 65from 1940-2000.
There was a slight decline in the number of aged people over 65 from1960-1980.
There was a fluctuation between 1 million and 1.2 million from1940-1950.