Waving a book in front of your face, you'll feel the air moving against your face.

在面前挥动一本书，你会感觉到空气在你面前流动。

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Dogs, for example, will wag their tails, get down their front legs, and stick their behinds in the air to indicate "what follows is just for play".

例如，狗会摇尾巴，放下前腿，把屁股翘在空中，表示“以下的动作只是为了好玩”。

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The doctor says you should point the device so the flow of air is just in front of your face.

VOA: special.2009.07.14

Holding a wireless wheel in the air in front of you is goofy no matter how you slice it.

ENGADGET: Sony PlayStation Move Racing Wheel hands-on (video)

Edney grabbed it out of the air in front of his own three point line, planted both feet and heaved the ball about 60 feet away just as the buzzer sounded.

WSJ

Boyd's strike partner, Kenny Miller, should have added to Motherwell's misery but had a fresh-air shot in front of goal.

BBC: Rangers 3-3 Motherwell