这里的主语是Laboratory scientists，但是后面跟了一个过去分词定语，其中分词中的介词又跟了一个-ing形式，-ing形式后又接了一个宾语和一个带有定语的状语。本句的谓语是are doubtless better than。 (来源：英语学习门户网站EnglishCN.com)

4.英语的信息末端原则的应用

    在英语中，信息含量大的部分往往出现在句子的末尾。这个特点一方面造就了一些非正常语序的句子，另一方面可以给我们提供线索，帮助我们正确理解英语中的长句。我们知道，一个信息发出者要表达丰富的信息，离开从句是寸步难行的。可是不管句子结构多么复杂，基本的句型还是只有五种。下面我们可以通过逐一的分析，探讨英语难句形成的规律。对于SV结构，由于英语句子一般是末尾的信息含量大，所以这种句子往往难以构成阅读困难，至多是主语位置有定语从句或者同位语从句。例如：（例子）。SVO结构的难点在于主语和宾语都可以连接定语从句；SVC结构也难以构成较复杂的句子；SVOC结构如果出现长句，那么往往是补语被调整到宾语的前面；SVOO结构也要注意哪个是直接宾语，哪个是间接宾语。

    SVOC：People often let their fear of speaking up and appearing more dull-witted than their peers interfere with their understanding.

    Derived from theoretical considerations and confirmed by observations, the velocity-distance law has made secure the concept of an expanding universe.

    下面请做练习三，辨认主句的基本类型。

    They would find relevant the antislavery attitudes of Northerners during the colonial period, the conflict over slavery in the Constitutional Convention, the Missouri Compromise, the militant abolitionist movement of the 1830? , and the Compromise of 1850.

    The study made clear that the working class that is so over-represented in crime statistics consists of lower-class people living in the lower-class areas of large cities.