题目

阅读理解Whenbuilding houses, people used to think about not only the climate of the areasbut also the building materials and the fashions for their houses. However,since electricity became more and more expensive, people began to pay much moreattention to the energy they could get for their houses and the new ways theycould find to protect their houses from both cold and heat.Now,houses of an old yet new type have been widely built. In some parts of theworld, people share their houses with their livestock(家禽). During coldweather, they gather their cows, goats, or other animals and keep已知 x 2 y 2 ，则 3 x 2 y 的值是（ ）A.0B.1C.3D.5