Where to start
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Test yourself
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Questions by topic
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The questions you have saved to come back to.
In the order you flagged them. Opening one shows it marked as you last answered it, and nothing you do there is scored.
A flag is a bookmark and nothing else. It does not move a question up or down the ladder, it does not change when the question comes back, and it does not count towards anything.
Unflagging is the only way a question leaves this list, and it can be undone straight away. Practising the flagged questions is a session like any other — the answers count, and a wrong one lands in your mistakes the same day.