It was about 600 years ago____the first clock with a face an

是的 “It is/was + 被强调部分 + that/who + 句子其他部分”是强调句型。除了谓语动词不能强调外，句子中其它成分都可以用该句型加以强调。 被强调的主语是人时，可用it is/was ... that/ who ...，但如果被强调的部分既包括人又包括物，只能用that。

对比一下 It was 600 years ago__when__the first clock with a face and an hour hand was made. when引导的是定语从句 再如 It was in the factory that I worked.-------------去掉强调结构： i worked in the factory 。 It was the factory （where） i worked.-----------定语从句 ： 去掉强调结构 i worked the factory

是的 ，很对