英国曼彻斯村经过100多年，变成了工业城市，生活在那里的桦尺蛾也由浅色品种多变成了深色品种，原因是（   ）

如图所示的几何体是由六个相同的小正方体组合而成的，它的俯视图是（　　）

    Hello. I'm Xu Wei. This is my sister, Xu Yi. And this is my brother, Xu Feng. This is my bedroom. Look, that is my new dress on the bed. I like it very much. My shorts are on the chair. My jeans are on the chair, too. That sweater isn't my sweater. It's my sister's. She's Xu Yi. The sweater is beautiful. I'd like one.

（范进）辞了丈人回来，自心里想：“宗师说我火候已到，自古无考场外的举人，如不进去考他一考，如何甘心？”因向几个同案商议，瞒着丈人，到城里乡试。