单选题 I couldn"t help ______ sorry for her. Her mother died when she was three.
【正确答案】 D
【答案解析】[解析] 根据本句句意：我情不自禁地同情起她来，因为她三岁时她妈妈就去世了。couldn"t help doing sth. 意为“情不自禁地干某事”，其中doing为动名词，属固定搭配。故本题答案为D。