Yes. Doctors' is plural.
One doctor: The doctor's care was excellent. More than one doctor: The doctors' care was excellent.
There can be one or more charts depending on the doctors a patient has.
doctor's (more than one doctor)
yes. they get paid alot more for knowing more than one language
No. Anesthesiologists tend to make more money because they specialize in one certain profession. Doctors can do practically anything. People pay more for specialized doctors because they have to go to school longer to practice their profession more thoroughly.
Is your brain more important than your liver? Try living without one. This is not really a question; teachers and doctors and absolutely vital to a healthy and enlighted society. We cannot do without either group.
yes. when there is more than one object
For any set of numbers, there can only be one mean, so it is not an issue that can arise. If you are working with more than one set of figures, then you can have more than one mean. What you do then is really dependent on what it is that you want to do with them, so there is no single answer to the question.
No. But there can be more than one data point which has the same value as the mean for the set of numbers. Or there can be none that take the mean value.
There is one arithmetic mean and one geometric mean to a set of numbers.
Yes, "statements" is the plural form of the word "statement," which refers to one assertion or declaration.
They are more educated than human doctors, who only need to learn about one species.