Arrows would continue to fly forward forever in a straight line were it not for gravity, which brings them down to earth.

要不是重力使箭掉落地上，它将会一直沿直线往前飞行。

《柯林斯英汉双解大词典》

Once Lion even saw several birds fly in line when he was in an airplane.

狮子还曾经在飞机上看见有几只鸟儿成一直线地飞翔。

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French officials said bad weather made the search difficult, with heavy clouds forcing planes to fly very low over the water and limiting their line of sight.

法国官方指出，恶劣的天气使搜索工作变得困难，多云天气迫使搜救飞机飞得很低，同时也影响了视线。

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Tom Shanklin - perhaps fortunate to still be on the field after a clumsy challenge in the air on Imanol Harinordoquy - got beyond the gain-line and from there fly-half Jones picked out Byrne's superb angle for the full-back to race 35 untouched metres to the line.

BBC: France 21-16 Wales

Gulfstream has recently introduced a new top-of-the-line 650 model that can fly 8, 000 miles without refueling at near-supersonic speed, reinforcing its reputation as the gold standard in business jets.

FORBES: General Dynamics Begins 2013 With New Leader, Changing Business Mix

All are following a similar line -- check before you fly, turn up early, expect tougher security and skimp on the hand luggage.

CNN: STORY HIGHLIGHTS