The world's population has grown to more than six times____it was in 1800.A.that B.what C.whichD.when

The world's population has grown to more than six times____it was in 1800.A.that B.what C.whichD.when
The world's population has grown to more than six times____it was in 1800.A.that B.what C.which
D.when

The world's population has grown to more than six times____it was in 1800.A.that B.what C.whichD.when
The world's population has grown to more than six times what it was in 1800.
答案是B
目前的世界人口与1800年相比已经增长到那时的六倍多!
短语grow to意思是“增加到”.类似的表达法还有increase to,rise to,climb to等.如：

这是一个主句和一个从句的关系，主句The world's population has grown to more than six times，从句it was in 1800，单看从句，句子完整不缺成分，肯定就不能选that/what/which，只有选一个时间状语。所以选when

选择B项，主要是当你问人口有多少的时候，我们会运用What is the population？句子中it指的是the world's population,整句话的意思：与公元1800年的人口相比，现在的人口是原来的六倍多。