如果纸质印刷品已经存在，在价格和易用性方面，电子版本与之相比情况如何呢？

If a print equivalent exists, how does the electronic version compare in terms of cost and ease of use?

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其连锁店网站提供了一个简单易用的与客户代表直接对话的程序，同时也通过电话和电子邮件提供服务。

The chain's website offers an easy-to-use live chat online with a customer service representative, as well as help via phone and e-mail.

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不过Forrester研究公司的分析员James McQuivey表示，这个价格几乎是一个6英寸电子书阅读器的两倍，而且易用性却只有它的一半。

But that's still almost twice the price of a 6-inch e-reader with half the convenience, says James McQuivey, an analyst with Forrester Research.

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So that means that we don't have to worry about things like wave functions when we're talking about Lewis structures, but because they're so simple to use and because they so often predict the electron configuration of molecules accurately, we end up using them all the time in chemistry, so it's very valuable to know how to draw them correctly and to know how to work with them.

因此这也就意味着我们在讨论路易斯结构的时候,不需要担心波函数之类的东西，但是由于路易斯结构不仅简单易用,而且用它来预测分子的电子排布,经常可以得到非常精确的结果，结果我们在化学中一直都在用它，因此知道如何正确地画出并运用,路易斯结构是非常有价值的。

麻省理工公开课 - 化学原理课程节选