A.thetimeB.whenC.thatD.which
答案C.强调句的结构是:It+be+强调部分+that(who)+主谓句。强调句的连词只有两个,that和who。当强调的部分是人,且为句子的主语时,才用"who",其余用that。
原句:Myfatherdidtheexperimentinthelabyesterdayevening.
强调主语:Itwasmyfatherwhodidtheexperimentinthelabyesterdayevening.
强调宾语:Itwastheexperimentthatmyfatherdidinthelabyesterdayevening.
强调时间:Itwasyesterdayeveningthatmyfatherdidtheexperimentinthelab.(注意不用when)
强调地点:Itwasinthelabthatmyfatherdidtheexperimentyesterdayevening.