How can I extend my Chinese visa?

hi,

i have applied for business type visa in chinese embassy ,as i am schedule to leave for china on 15 october 2012.The purpose of my visit is 2 months training in the chinese company.I am applying for visa in india.Kindly clear my following doubts:-

(a) can business visa be granted for 60 days validity?

(b) In case i am provided visa for only 30 days ,how can i extend my visa validity by another 30 days in china as i need to complete my training.