Some amphitheaters could be filled with water so that ship battles could be fought.一些这样的圆形竞技场还会被注满水以便表演海上作战的船只能够航行.In 7 th century BC, Romans inherited the traditions of Greece and built racetracks and unroofed amphithea...
Well, maybe I stumped you on that one.好吧，也许我在那件事上使你为难了。The Marshal stepped over the vacuum-cleaner and stumped out of the room.元帅迈过真空吸尘器，脚步沉重地走出了房间。John is stumped by an unexpected question...一个意想不到的问题把约翰难住了。Will you hel...
The upper side of a leaf is known as the adaxial surface.叶子的上部被称为近轴面.The abaxial stomatal resistance was smaller than the adaxial.叶片正面的气孔阻力小于叶片反面对应部位的气孔阻力....