Why do doctors tell patients to complete their course of antibiotics?

To check how many times the patients ever take the antibiotics, this will stop the infection from returning, as well as reduce the risk of the bacteria becoming resistant to the antibiotics.

If you already use the antibiotics a lot, the bacteria can be resistant and stronger ofc. which antibiotics not longer work.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.