It can help you learn English effectively.

【Auto-Renewal Subscription】
- Subscription periods: monthly, half-yearly or annually.
-The auto-renewal service applies prior to the expiration of an active subscription. By enabling auto-renewal, within 24-hours prior to the end of the current subscription period, payment of the same subscription will be automatically deducted from your iTunes account. The exact payment amount corresponds to the following subscription periods: monthly, half-yearly or annually.

-Auto-Renewable Subscriptions protocol: https://damonchen117.github.io/diandubi/protocolEN.txt
-Privacy Terms: https://damonchen117.github.io/diandubi/privacy.txt