强调句的基本结构是“It+be+被强调成分+that (who/whom)…”.
It was Jim that told us the news.（强调句型的陈述句形式）
Was it Jim that told us the news?（强调句型的一般疑问句形式）,一般疑问句,只需把be提前.
Who was it that told us the news?（强调句型的特殊疑问句形式）,只需在一般疑问句前加上疑问词,可视为对陈述句强调中的被强调成分提问得来（对Jim提问）
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1.强调句型特点是：去掉It be …that/who…,句子成分完整.
It is in the street that I met her 强调句 把it is that 去掉,句子完整,in the street I met her.
It is clear that not all boy like foot ball,去掉后,clear not all boy like football不完整,不是强调句（是主语从句）
2.强调句中只有that/who/whom,不会出现where,which,when等.
It is the street where I met her 定语从句 where 关系副词 做定语从句中的地点状语；
3.如果强调时间地点 就看前面有没有介词,It is in the morning/at some place that.一般情况下就是强调