Keywords: galaxy evolution, the circumgalactic medium, quasar absorption line spectroscopy

1. INTRODUCTION

2. DATA ANALYSIS 

2.1. Datasets

3. RESULTS

3.1. Observed properties of galaxies associated with MgII absorbers

3.2. Redshift evolution of gas distribution

3.3. Gas distribution in dark matter halos

4. DISCUSSION

4.1. Comparisons with previous studies

4.2. Origin(s) of MgII absorbers

5. SUMMARY