Yes, 冠詞特化for英会話 is completely free and it doesn't have any in-app purchases or subscriptions.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
冠詞特化for英会話 is free.
To get estimated revenue of 冠詞特化for英会話 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.