单选题 Knowledge is a comfortable and necessary retreat and ______ for us in an advanced age; and if we do not plant it while young, it will give us no shade when we grow old.
【正确答案】 C
【答案解析】ingredient“原料,要素”;reliance“信赖,信心”;shelter“庇护,避难所,遮 盖物”;inclination“倾向,爱好”。根据句意和各个选项的意思可知,正确答案是c。