Can i stay in China enter before date to duration stay date ?

Dear sir, i have F category chines multiple visa for one year, but which issue date:19AUG 2010 and enter before 19 AUG 2011 Duration of each stay 010 Days after entry, now i would like to know if i enter on 15 AUG 2011 from that day to 10 days can i stay in china ? or within 19 AUG 2011 i must leave china ?
Please give me reply, Thanks ----Ashraf Uddin, Dhaka