No, 常春藤基础英文词汇 is not free (it costs 19.90), and it also contains in-app purchases.
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常春藤基础英文词汇 costs 19.90 to download (and they also have additional in-app purchases).
To get estimated revenue of 常春藤基础英文词汇 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.