n. 双门齿型
1.The koala has one of the smallest brains in proportion to body weight of any mammal, being 60% smaller than that of a typical diprotodont, weighing only 19.2 g.
考拉大脑和身体的比重是哺乳动物中最小的之一，比它所属的双门齿型有袋动物的平均值小了60%，重量只有19.2克（就一个核桃那么大）。
2.The koala has one of the smallest brains in proportion to body weight of any mammal, being 60% smaller than that of a typical diprotodont, weighing only 19.2 g.
考拉大脑和身体的比重是哺乳动物中最小的之一，比它所属的双门齿型有袋动物的平均值小了60%，重量只有19.2克（就一个核桃那么大）。