30 percent of reptiles, birds, and fish are currently threatened with extinction.目前，30%的爬行动物、鸟类和鱼类面临灭绝的危险。All reptiles have to slough their skin to grow.所有爬行动物生长过程中都要蜕皮。Snakes and crocodiles are both reptiles.蛇和鳄鱼都是爬行动物....
Doing crosswords gives the mind some exercise.做纵横字谜游戏能锻炼脑筋.I keep a dictionary beside me when I'm doing crosswords.我填纵横字谜的时候,手边总有一本字典.I'd say crosswords to me are probably an obsession.字谜游戏对我来说或许是一种困扰....