一道高中英语题

a
,我认为从句中疑问句用正常语序，这是一个强调句，没有具体时间无法还原，
People seemed to have forgotten it was x years ago that the ....

强调句的结构是 it+is(was等系动词适当形式)+被强调部分+that(who)+句子其他部分。

比如说，他昨天在图书馆读了三本书，普通的叙述方式为： He read three books in the library yesterday. 如果要强调他，则为：It was he who(that)read three books in the library yesterday.如果强调三本书，则为：　It was three books that he read in the library yesterday. 如果强调在图书馆，则为　It was in the library that he read three books yesterday. 被强调部分是人的时候可以用who也可以用that.
你所举的句子强调的时间状语，即how many years ago。这里是强调句的特殊疑问句形式，一般的语序应为： How many years ago was it that the power stations were built there?. 必须要认识到，这个特殊疑问句在你所举的复合句中充当宾语从句的成分，在英语语法中，如果疑问句充当从句，则使用正常语序，不倒装。所以应为：
People seemed to have forgotten how many years ago it was that the power stations were built there.

理解了吗？

it was ……that …… 是强调句型，强调部分为it was 后面how many years ago
陈述句为：
It was 16 years ago that the power stations were built there.
对此句提问为：
how many years ago was it that the power stations were built there.
在原题中此句做宾语，语法规则是疑问语序变为陈述语序，则为A答案。

你好，这个是一个强调句的疑问句。
还原后为
People seemed to have forgotten it was how many years ago that the power stations were built there

A 宾语从句后加肯定句语序，加上后面的句子是强调句，选A

强调句。。