Could I leave my passport at Chinese Embassy for just a few days, even if the total time to get a visa can be much longer?

1) What type of visa do I need to attend a scientific meeting in China? The costs are paid entirely by Danish funds.

2) I need my passport for other travels over 4 of the 6 weeks before leaving for China. How should I arrange things -- could I leave my passport at the Chinese Embassy for just a few days, even if the total time to get a visa can be much longer?

Thank you for your attention.