单选题It was she that ____

问题补充：

单选题Itwasshethat________asharpwhistle,whichmakes________possibleforustocatchthethief.A.gave off; thisB.gave out; thatC.gave; itD.sent out; them

答案：

C解析前半句即主句是强调句，强调she；后半句是which引导的非限制生定语从句，it为形式宾语，指代真正的宾语即动词不定式短语to catch the thief.