Typically you can pre-buy credits and then just download images when you need them.

只要在网站上预存了一定款项就可以下载你需要的图片。

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Phillips bought market share, mainly by giving sellers lavish guarantees, promises to buy items at pre-agreed prices if the bidding failed to go high enough.

菲利普拍卖行主要靠给卖家慷慨的保证来抢占市场份额，它向卖家许诺，一旦竞价过低公司将以双方之前协定的价格购买拍品。

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Customers can buy pre-determined prescription strength lenses, or simply buy lenses with no prescription, without the need for an eye exam, which adds to the potential danger.

顾客不需要做任何眼部检查就可以买有视力矫正的美瞳，也可以买没有度数的美瞳，这也增加了潜在的风险。

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Still, the pre-buy facility must be judiciously selected and the inspection must be carefully monitored in person.

FORBES: What's The Best Jet For You? (Part 3)

We have had a little pre-buy effect because Euro 4, the latest emissions standard, was valid from the first of October.

FORBES: Big Trucks On A Bumpy Road

Visa points out that non-Visa card holders can buy a pre-pay card for the duration of the Games.

BBC: Olympics 2012: Fans must use Visa for tickets