Extend tourist L type.

I have a 'L' type, (2 entry × 30 days) for China. I am currently in Xi'an.

My question is, is it possible for me to extend my stay during the 1st entry?
Does it effect my 2nd entry in any way?
And will it be possible to extend my 2nd entry if i have extended my 1st entry?

Any info will be great. Cheers.