高中英语定语从句和名词性从句综合训练
名词从句
名词从句有四类：宾语从句、主语从句、表语从句、同位语从句。例如：
宾语从句：I don’t know where he will go.
主语从句：Where he will go is unknown.
表语从句：The problem is how we can get so much money.
同位语从句：We all feel sorry about the news that he failed in the game.
下面几点是学习名词从句要加以注意的：
1． whether和if都可以引导宾语从句表达“是否”意，（即引导宾语从句时if和whether
   可以互换）但以下几种名词从句要用whether（不用if）引导：