Start as shown with the arms extended, back flat, legs fully extended and the balls of the feet on the Swiss ball.

开始动作如图所示：两臂伸直，背部保持平直，两腿充分蹬伸，脚掌置于健身球的球体之上。

youdao

I have this theory that, to us the world is a flat thing we stand on, but to birds it is a cliff they cling to, a huge ball and they cling to the side and then fall off and fly and glide.

我有一种想法，就是对我们来说世界是一个我们所站立的平坦的东西，而对鸟来说是一个它们所依靠的峭壁，一个巨大的球，它们依靠在边上，然后离开、飞翔、滑行。

youdao

Lean on the ball as shown, keep the back flat or maintain its natural curve, with the legs straight.

身体俯卧于球体之上，动作如图所示。背部保持正直或保持自然弯曲状态，腿部伸直。

youdao

A ball of clay is placed on a flat wheel device that turns quickly.

VOA: special.2009.09.09

Owen's goal, on 17 minutes, came after Riise lobbed the ball over a flat-footed Joos Valgaeren.

BBC: SPORT | Football | Liverpool thrash Celtic

Playing a wider game, Ireland attempted to concentrate on working the outside channels with the dangerous, quick, flat ball rather than grunting and boring their way through the packed close-in defenders.

BBC: Ireland coach Eddie O'Sullivan

India's prolific domestic cricket is played on dull, flat tracks, which make most of its batsmen vulnerable to the moving ball and bouncy pitches overseas.

BBC: Indian cricket's end of an era