强调句.
It is/ was + 被强调部分+ that/ (who/whom)（强调主语且指人可用who,强调宾语且指人可用whom）+ 其它部分.
e.g.I met him in the street this morning.
It was __I__that /who met him in the street this morning.（强调主语用主格）
It was _him___that/whom I met in the street this morning.（强调宾语用宾格）
It was ___ __in the street__ ____ that I met him this morning.（强调地点状语）
It was ____ this morning_____ that I met him in the street.（强调时间状语）