Professor from university of xihua in china Part 1

40 secs

4 mins 10 secs

1 hour 32 mins 44 secs

12 mins 23 secs

3 mins 48 secs

1 hour 35 mins 34 secs

26 mins 31 secs

5 mins 8 secs

2 mins 55 secs

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1 hour 33 mins 21 secs

45 secs

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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

13 mins 55 secs

10 mins

15 mins 1 sec

21 mins 50 secs

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15 mins 4 secs

7 mins 30 secs

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45 mins 10 secs

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11 mins 31 secs

30 mins 21 secs