The first instance is the service or software that offers a free trial and then converts users into paying customers.

实例之一是服务或软件首先提供免费试用，然后将免费用户转化为支付费用的顾客。

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Offer a special deal, extra service or a lower price during your trial/introductory period.

在此期间提供优惠，额外的服务或者低价。

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For nearly a month, a trial version of CNN's wire service has been on display in some newspapers.

一个月前，CNN电讯稿的试行版已经开始出现在部分报纸上。

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One of the report authors, Dr Robert Clarke, from the Clinical Trial Service Unit at the University of Oxford, said that the findings were "reassuring".

BBC: Folic acid 'cancer risk' fears played down by study

On Sept. 15, Rory Collins, the head of the Clinical Trial Service Unit at Oxford, was called by Merck and told of the SEAS result, according to the letter.

FORBES: Magazine Article

The trial service will cover three rural general hospitals and 13 community hospitals within Argyll and Bute, Lochaber, Skye and Lochalsh, Wigtown, Western Isles, Arran, Cumbrae and Kinloch Rannoch.

BBC: NEWS | UK | Scotland | Medical airlift service extended