A-A+
It is thought that one billion people
问题详情
It is thought that one billion people I the world,
_
is half the word’s workers, earn their living by farming.
A．ifB．thatC．whichD．what
网友回答
B
解析句中“half the world’s workers”是对“one billion people in the world” 的补充说明， “that is”是 “that is to say”的省略说法，是插入语，that 并不是引导非限制性定语从句的，如果在 “that is”后加个逗号则更清楚，应B。
知识点
therebe句型的定义
there be句型的概念：
英语中的there be结构主要表示某处存在有某物，所以通常被称为存在句。其中的there为引导词，无词义，be为谓语动词，therebe后面的名词为句子主语。