1. Representation of set (1)Listing elements, One way is to list all the elements of a set when this is possible Example: The set A of odd positive integers less than 10 can be expressed by A={1,3,5,7,9}。 B=x1, x311. Representation of set (1)Listing elements, One way is to list all the elements of a set when this is possible.. Example：The set A of odd positive integers less than 10 can be expressed by A={1, 3, 5, 7, 9}。 B={x1 ,x2 ,x3 } √