The sort usually performs fewer exchanges than the sort.

The two words that complete the sentence are: selection and bubble.

The complete sentence is: The selection sort usually performs fewer exchanges than the bubble sort.

Both, selection and bubble are sorting algorithms used in computer programs. This is they are procedures to arrange data.

Bubble is the most simple algorithm but it is too slow and impractical, so selecting sort, still simple, performs better than bubble sort.

Selection sort divides the list of data into two parts: one contains the data already sorted and the other has the part of data pending to be sorted.

Bubble sort goes through every pair of elements, compares the two data and moves them if necessary.

Ithink it is a thermometer.