Yes, 英文法: 形容詞 is free to download, however it contains in-app purchases or subscription offerings.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
英文法: 形容詞 has several in-app purchases/subscriptions, the average in-app price is ¥1.00.
To get estimated revenue of 英文法: 形容詞 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.