( )
2.
4/7
5/7
6/7
7/7
: http://www.youtube.com/watch?v=Iv9rRFzppO0
http://www.youtube.com/watch?v=FHofO538HyM
http://www.youtube.com/watch?v=pn3cA10W7TI
http://www.youtube.com/watch?v=zmghnwJbGF4