6-8:
http://wenku.baidu.com/link?url=28M-6hTamRUf6LnEKx34GLLME0dYFh0nkc1DnftCjT1Ca2nQqZ70RMxMkzkiW2vFwQEpOqg2WibO-Djm_P-HdxRVtD6syfBuJgoN-RXmIIy
6-9:
http://wenku.baidu.com/link?url=Eum5GUJKMlhsYCpZlS4Bdvc5eXFx60ibHKu2Bm6UpwEBidbYFrz5GUPKr89rvX3Oso5e0uQmXFe8dzpJLYEEYOSGB9QPfZPOXrBHnxQhhea
6-17:
http://wenku.baidu.com/link?url=3B2xUWeB3fJD_WOa4G_PbjMvm9_z66OwH43wlNr9Fks50dh-An04jckQS8khx73nwrtkUpdNwDU3PHS9tTriNEdDHx3cnFvWeKU5EF0l-S3
6-18:
http://wenku.baidu.com/link?url=p7cFieAHgyNXojSsAAWELrFnT_VeelY-WMPW8OJDItXWlZbBQpIqzn-0KzfwFKtfNAAFK3BjGEaopqp9AZ_kRs4_HLiu9PFAFscwmTj77Ny