文法問題，as great a source of astonishment then as - 英檢

眾文TOEFL iBT 托福分類字彙，第32篇，Railroad

第一段中間

The new steam machine was as great a source of astonishment then as the computer is today.

書上的翻譯是，"當時嶄新的蒸汽火車就像現在的電腦一樣"



翻譯基本上沒問題，但是中間的那個a source of astonishment then，文法上是要怎麼解釋呢？

如果只是，The new steam machine was as great as the computer is today.

這樣也是表達同樣的意思吧？

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