完全同意黎老师和罗老师的看法，尤其是罗老师从另一个角度对这位的问题作了分析，对于强调句的学习很有帮助，事实上只要记往哪些不能用于强调句，其余的也就可以用于强调句了。我从词典上找了几个相关的例句，供提问的朋友参考：
It was here that he differed from an Englishman. 他和英国人的不同就在于此。
It was therethat I met Ernest Hemingway and Ford Maddox Ford. 我就是在那儿遇到了欧内斯特·海明威和福特·马多克斯·福特。
It was just then that I chanced to look round. 就在那时，我恰好环顾了下四周。
It is now that the spadework has to be done to lay firm foundations for later success.  现在应该着手做一些准备工作以便为日后的成功打下坚实基础。

▲“被强调的成分”通常不能是表语、谓语动词、though/although引导的让步状语从句或whereas引导的从属分句等。但是，如果当系动词不是be,且表语部分是名词性词组时，强调句也可以强调表语。如：
①The pictureis wonderful.
→It is wonderful that thepicture is. (×)
②He becomeshead of the department now.
→It is head of the department thathe becomes now. (√)
▲“被强调的成分”是原因状语从句时，只能强调由because引导，而不能强调由since/as/why 等引导的原因状语从句。
It was because the water hadrisen that they could not cross the river. (√)
It was since they’ve obviouslyforgotten to phone me that I’ll have to phone them. (×)