请看下面这道题：
He wrote a lot of novels, most of _________ were popular.A. them B. whom D. that D. which
【分析】此题最佳答案为D，但很容易误选A。假若单独看 He wrote a lot of novels 和 Most of them were popular 这两句话，它们并不错，但将它们放在一起用逗号连接就不甚妥当了。因为，英语句子按其结构来划分，可分为简单句、并列句、复合句和并列复合句四种，也就是说，一个规范的英语句子，从结构上说，它必须隶属以上四类句型之一。但上面一题若选A，则它既不是简单句(因为它有两个主谓结构)，也不是并列句()，也不是并列句因为它没有并列连词)，也不是复合句(因为它没有主从句之分)，当然它更不是并列复合句，所以选A是错误的。可以选D，是因为空白处填了 which 之后，后一句即成了一个非限制性的定语从句，前一句即为主句，整个句子即为一个复合句。比较以下各句：(1) He wrote a lot of books, and most of them were popular.句中用了并列连词，整个句子为并列句。(2) He wrote a lot of books, most of which were popular.后一句用了 which，使之成为定语从句，整个句子为复合句。(3) He wrote a lot of books, most of them being popular.后一句用了非谓语动词 being，故逗号处不用并列连词，整个句子为简单句。