I know some nouns in the use case scenario are candidate to be class, for example member, customer, student ....I can find such entities and some attributes of them, but my problem is that I can't easily find any method for these classes.Which part of use cases are candidate for methods or functions of classes?Please give some examples.For example in a system for hospital, Patient or Doctor are classes, what are the functions for these classes? 
Finding methods of classes from the use case
class diagram;use case