GDP deflator is an （       ）price index, whose weights (       ) over time; while CPI is an (        ) price index, whose weights remain (       ) over time.

To fill in the blanks in your statement about GDP deflator and CPI, we can explain them as follows:

1. Nature of Index:

   • GDP deflator is an output-based price index.
   • CPI (Consumer Price Index) is an expenditure-based price index.

2. Weights Over Time:

   • The weights of the GDP deflator change over time as they are based on current production and consumption levels.
   • The weights of the CPI remain constant over time, reflecting a fixed basket of goods and services.

So, if we fill in the blanks, the complete statement will be:

"GDP deflator is an output-based price index, whose weights change over time; while CPI is an expenditure-based price index, whose weights remain constant over time."

This distinction highlights the different methodologies used to calculate these indices and the implications they have on economic analysis and inflation measurement.