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When can you not make a u-turn other than the sign that says, don't?
Other than this sign http://image.shutterstock.com/z/stock-photo-do-not-u-turn-sign-board-traffic-219264649.jpg I mean. Say the sign disappeared or is obscured somehow, why/how would you know to not make a u-turn?
In other words, In a written driving test exam, what would the answer be?
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