Ned's build was strong and tall compared to his own shorter, wiry one.
兩個人的體格比較，這原句的compared可以改用comparing嗎？要如何理解文法，何時用-ed 與何時用-ing 呢?

體格不會主動比較，是被拿來比較

不行，compared這裡算被動，Ned’s build was tall (when) compared (by some observers) to his.Comparing Ned’s tall build to his own, his was shorter.前面comparing例子是He compares Ned’s build to hisown,是主動。

終於弄懂了，不懂好久，感謝解惑

上面(by some observers)是(by himself)才對，打錯