introduction管 （611） 16

9 mins 53 secs

4 mins 29 secs

12 mins 33 secs

9 mins 32 secs

3 mins 45 secs

15 secs

1 min 19 secs

1 min 43 secs

51 secs

1 min 30 secs

1 min 20 secs

1 min 18 secs

1 min 27 secs

1 min 3 secs

1 min 32 secs

2 mins 8 secs

1 min 21 secs

1 min 3 secs

1 min 21 secs

1 min 4 secs

55 secs

1 min 4 secs

1 min 6 secs

25 secs

13 mins 43 secs

13 mins 38 secs

49 secs