埋头于某事：bury oneself in sth .
Dear Xiao Lin,
I have had a busy holiday these winter because I will take part in the entrance examination this September.
I almost buried myself in the books every day. I had to go over every required subject and did a lot of exercises. I worked very hard, more than 10 hours a day. When I was tired I watched TV for a while and listened to music, but I never went to the cinema or theater. I had to refuse several invitations from my relatives and classmates. I only called them to greet them on the eve of the Spring Festival. How I wish there were no examinations at all, but of course it is impossible. I will try my best to get better results and go to were no examinations at all, but of course it is impossible. I will try my best to get better results and go to Qing Hua University, which I have been longing for. How is your vacation? Best wishes to you and your family!