Modelling atomic and molecular gas and the radial profiles in SAMs.

In this talk, I will introduce the recent progress in L-GALAXY semi-analytic models of galaxy formation, especially on the HI and  H2 gas components and the radial profiles. I will mailny include following topics: the size-mass relation of HI gas component, the radial profiles of metallicity on galaxy disks, the HI gas prediction at high redshift for FAST telescope.