名词性从句Nominal Clauses 名词性从句是由if, whether, that 和各种疑问词充当连接词所引导的从句，在句子中起名词作用。 名词性从句的功能相当于名词词组, 它在复合句中能担任主语、宾语、表语、同位语等，因此分别称为主语从句、宾语从句、表语从句和同位语从句。引导名词性从句的连接词引导名词性从句的连接词可分为三类： 连接词：that, whether, if (不充当从句的任何成分）连接代词：what, whatever, who, whoever, whom, whose, which.连接副词：when, where, how, why 中世纪，普遍相信地心说(geocentric theory)。 Geocentric theory was wildly believed in the Middle Ages. Geocentric theory: the earth is the center of our planetary system That the earth is the center of our planetary system was
