Hi, I am in Hangzhou since may 30th, when i arrived i had a multiple entry visa, but just can stay 30 days each time, so i needed stay more and extended my visa for 2 months and cancel the multiple entries, after 2 months i extended again per more 2 months, now my visa is until october 25th, can i extend my visa again? have a limit of times or of period that can extend the visa? Thank you in advance!