I greatly appreciate ________ my son's life.
A.you to saveB.your having savedC.you by savingD.you to have saved在线课程B
句意：我非常感激你挽救了我儿子的生命。appreciate只能接v.-ing形式作宾语，B项是动名词的复合结构，A、D项用动词不定式作宾补，即appreciate sb. to do sth.也不是正确结构。