3.there + be
此简单句型一般用于对于上述两种动态数据描写句型进行同义转换，be动词的时态一定要根据数据的时间来改变，否则很容易出错：
I.There was an increase in the visits from about 12 to 53 million from 1979 to 1999.
II.There was a sharp rise in the number of visitors between 1995 and 2005 inChina.
III.There was a slight decline in the number of aged people over 65 from 1960-1980.
IV.There was a fluctuation between 1 million and 1.2 million from 1940-1950.
