among civilized people it was once thought that ginger root by some magical power could improve

题目

among civilized people it was once thought that ginger root by some magical power could improve
the memory.这句话前部分可以这样翻译吗：在文明人中曾经以为……“　it前面不用加什么连接吗?　　这句话中的by是什么意思?为什么用by?可以用其它词代替吗?这里是“有魔法”的意思,能用have吗?　　　　could前面也不要连接词的么?　　不懂啊~~~~

答案

你翻译的很好：在文明人中曾经（有人）认为…by some magical power 介词短语,意思是 “通过某种魔力）,作方式状语.by "通过.”又如：He earns his living by writing (他通过写作谋生） by不能用其他词代替that gin...