During period of isolationism why were the Chinese successful in  improvising new rules governing trade with foreigners

Why is it useful for historians to base certain studies on the analysis of historical themes

According to this contract, when will the sharecropper receive his payment?

Is the weather changing? consider the data of severe weather that includes tornadoes occurring throughout the u. s. over the last four years. compare the severe weather for the last three years. then compare the first three months of 2017 with that data. based on previous years, what might the prediction be for weather during 2017?