Professor from university of xihua in china Part 1

40 secs

4 mins 10 secs

1 hour 32 mins 44 secs

3 mins 48 secs

1 hour 35 mins 34 secs

26 mins 31 secs

23 mins 5 secs

1 hour 33 mins 21 secs

45 secs

6 mins 26 secs

13 mins 16 secs

2 hours 8 mins 52 secs

2 hours 1 min 21 secs

16 mins 53 secs

12 mins 17 secs

2 hours 8 mins 54 secs

8 mins 5 secs

5 mins 6 secs

5 mins

4 mins 36 secs

2 mins 14 secs

28 mins 11 secs

20 mins 42 secs

10 mins

6 mins 20 secs

5 mins 31 secs

15 mins 1 sec

15 mins 1 sec

15 mins 1 sec

15 mins 1 sec

15 mins 1 sec

15 mins 1 sec

7 mins 30 secs

15 mins 10 secs

45 mins 10 secs

6 mins 31 secs

30 mins 21 secs

12 mins 23 secs

13 mins 55 secs

11 mins 31 secs