ARO is a spaced repetition (SRS) tool for memorizing English sentences and phrases through fill-in-the-blank practice.

The name ARO comes from a Korean word meaning "to engrave deeply in the mind." Repeat, fill in, and let the sentences sink in.

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Key Features
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▸ Automatic sentence extraction
Paste any text and ARO automatically picks out English sentences and short phrases. Korean text and line breaks are used as natural dividers. Preview and select exactly what you want to save.

▸ Fill-in-the-blank practice
A word in each saved sentence is hidden as a blank. Choose the correct option from the given choices to check your answer. The blank is placed at a different position each session, so you practice the full sentence from multiple angles.

▸ Spaced repetition scheduling
Answer correctly and the next review is scheduled further away. Answer incorrectly and the sentence comes back sooner. Review intervals start at 10 minutes and extend up to 120 days. You only see what is due today.

▸ Sentence list and editing
Search or sort your saved sentences by accuracy. Edit sentences that were extracted incorrectly, or delete ones you no longer need.

▸ Stats
View total sentence count, today's practice count, accuracy rate, SRS stage distribution, and the last 7 days of practice activity.

▸ Backup and restore
Export all sentences to JSON or CSV, or import them back.

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Privacy and Data
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All learning data is stored only on your device.
No login, no account, no server, no cloud sync.
Works completely offline.

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Other
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Dark mode support (follows system setting or manual selection)
Available in English and Korean