3.背熟：it was almost impossible to attach hawsers and chains to the rim without damaging it.

短语：attach to 把......连在......上；附加，使属于

attach == tie 栓，系

短语：rim ==  the sides of the dish

结构分析:双重否定：not + without

4. Eventually chains were fixed to one end of the disk and a powerful winch was put into operation.

短语：Eventually == at last 语气比at last 强烈得多，

终于：强调失败的结果用in the end  表示成功用at last, eventually

eventually 重点强调经过努力而终于......

finally   只表示顺序的最后

短语：put into operation =  use