By burning tree branches, pine needles, and pine cones, many not only warm their houses but improve the smell therein.许多人在家里烧树枝、松针和松果，不但给房子取暖，还改善了屋里的气味。In the pines squirrels commonly chew off and drop entire cones.松树上的松...
风能作为动力的成功是对可再生能源一次立见分晓的检验。The success of wind power represents a litmus test for renewable energy.科学家们正在为发明一种能储存这种动力的方法而工作.Scientists are working to devise a means of storing this type of power.并不是所有烃类的储集都必然是水动力的结果.Not a...