这个句子怎样转为被动语态？

storage on magnetic media is employed by external memory.

storage is employed by External memory on magnetic media

storage on magnetic media is employed by external memory.或者storage is employed by External memory on magnetic media

以上都可以啊，那么简单的说~把句子成分分析清楚了就不需要弄懂没个词的意思了

storage is empliyed on magnetic media by external memory.