Question

It remains doubtful ______ immediate measures could be taken to prevent underground water pollution.

A．how

B．whether

C．that

D．where

Answer 1

B

试题分析：考查主语从句。本句中的it是形式主语，真正的主语是后面的whether immediate measures could be taken to prevent underground water pollution.因为主句的谓语部分是remains doubtful仍然很怀疑，说明是不确定的事情，故使用whether。句意：是否会有立刻的措施被采取来阻止地下水污染仍然值得怀疑。That引导的主语从句表示的是确定的事情，AD项的句意不相符。故B正确。
点评：在复合句中做主语的从句叫做主语从句，它的位置与陈述句基本结构中的主语相同。引导主语从句的关联词有：连词：that, whether；连接代词：who, whom, whose, what, which；连接副词：when, where, why, how；复合词：whatever, whoever, whomever, when?蛳ever, wherever, whichever, however.解答这类题目，关键在于分析清楚句子结构。通过判断引导词在从句中所作的成分及意义，来选择正确的引导词。