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straight (ahead); direct; upright; erect
straightforward; honest; frank
真っ直ぐ行くと駅です。
Go straight and you'll reach the station.
真っ直ぐ立ってください。
Please stand up straight.
この道を真っ直ぐ進めば学校が見える。
If you go straight along this road, you'll see the school.