应该说Used it to be thought that the earth was flat吧答案选Used it be thought that the earth was flat觉得不大对劲儿
问题描述：
应该说Used it to be thought that the earth was flat吧
答案选Used it be thought that the earth was flat觉得不大对劲儿
答
我支持答案的选择
used to do。。后接动作
此处纯粹是陈述一个观点---过去认为地球是方的。无动作意义，不用用to
答
it used to do sth表示过去常常做什么
它的疑问和否定都有两种表达
疑问：used it to do./ did it used to
否定：it usedn’t to do/ it didn't used to
你的提问就是陈述句it used to be thought that ther earth was flat.采用了第一种疑问式变成的疑问句.以前人们认为地球是平的吗?