短语词组短语back bone lining up machine 书脊粘纱布机bone up detail 抓紧温习bone up World 努力研读bone up on 努力研读;专心致志于;专门钻研;钻研to bone up on 钻研bone up for 突击钻研bone up to 学习bone up on a subject 专攻一门学问Bone up on a problem 突击钻研一个问题 返回 bone up