问题
选择题
The world’s population has grown by ______ it was in 1800.
A．more than six times that
B．six times more than that
C．more than six times what
D．six times as many as
答案
答案：C
此题考查倍数表达，句意：世界的人口应经增长到1800年的六倍多，后一个分句中was后面缺少表语，故用what,所以选C。