题目

用方框中所给单词的适当形式填空，使短文通顺、正确、连贯 (每个单词限用一次)。 but   carry   to   tradition   buy   even   a   choose   they   cheap Twenty-First Century Books Probably you have seen someone reading a book on an electronic reading device. Over the past few years, these small computers have become more popular. For that reason, more companies that make   1   paper books are now making electronic books (ebooks). Most ebooks are the same as paper books,   2   people download a file into a reading device rather than �sin18°等于（    ）A.cos20°cos2°+sin20°sin2°B.cos20°cos2°-sin20°sin2°C.sin20°cos2°+cos20°sin2°D.cos2°sin20°-cos20°sin2°