The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen.

最好的信号不仅取决于它的亮度，还取决于它与背景的对比度。

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By selling the helium, the government can not only pay off that debt but reduce its overall debt as well.

政府通过出售氦不仅可以偿还债务，还可以减少总体债务。

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GPS, which uses signals from satellites, only works well outside and its co-ordinate system only identifies areas down to a few metres in diameter.

BBC: Let your text messages linger

So, in that regard, GM is doing well to not only widen its product range but also offer customers the option of petrol or diesel variant.

FORBES: GM Stock Good For Drive To $25 With Room To Improve In India

Unicom has struggled, signing up only 30 million CDMA customers--well below its capacity of 70 million--a subscriber base only a sixth the size of that of China Mobile, the dominant GSM carrier.

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