As obscure as the middle class definition is, it is most fascinating to me how we Americans expend so much energy trying to maintain the appearance of wealth.
中产阶级的定义是这么模糊，最令我好奇的是我们美国人怎样耗费如此多的精力努力维持富裕的表象。
2
Not only is the tower's appearance striking, it also combines residential, office, commercial, and growing space with renewable energy generation, water collection and a sophisticated cooling system.
Brown fat has a darker appearance because the tissue is metabolically active — which means it burns energy and calories, in contrast with white fat, which just sits.