Student visa and L visa

Hi,

I currently have an L and will be entering China in May, I will be visiting friends. I will also be taking part in a university course for 4 weeks, beginning in July and have been told by my university that it is necessary to buy the student X. After the course ends I will be staying in China longer.

I am wondering if there is an alternative to buying the student X, also, if I do need the student X, will my one month studying contribute to the 90 day maximum on my L?

Many thanks.

David