Even though it is not a perfect measure, economists can use real GDP to i. compare how the value of the goods and services produced in China have changed over the past 10 years. ii. look at the length of recessions and expansions in the United States. iii. compare the standard of living in China versus the standard of living in Vietnam

 i, ii and iii

Explanation:

Gross domestic product is the sum of all final goods and services produced in an economy within a given period which is usually a year.

Real GDP is GDP that excludes the effect of price level changes. It has been adjusted for inflation.

When the gdp of a country for two consecutive quarters is negative, it means the country is in a recession.

By adjusting for changes in price level, real GDP helps us to compare changes in he value of goods and services

Real GDP per capita helps us to compare standard of living among different countries.

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