Listening 17. (No. 45~46)
https://www.youtube.com/watch?v=VSITBwyqIk4&list=PL6D-YTosvGYq8YexsOG53BGav1CD0t3aM&index=30
Listening 18. (No. 47~48)
https://www.youtube.com/watch?v=80iJYOrGfcc&list=PL6D-YTosvGYq8YexsOG53BGav1CD0t3aM&index=52