Listening 5. (No. 17~20)
https://www.youtube.com/watch?v=S_pJiVzluNM&list=PL6D-YTosvGYq8YexsOG53BGav1CD0t3aM&index=18
Listening 6. (No. 21~22)
https://www.youtube.com/watch?v=L86mxCjl0BE&list=PL6D-YTosvGYq8YexsOG53BGav1CD0t3aM&index=19