此外，尽管人类直立行走已经有数百万年的历史，我们的脚和背部仍在两足行走的姿势中艰难斗争，无法轻易承受过长的四肢持续施加的压力。

Moreover, even though humans have been upright for millions of years, our feet and back continue to struggle with bipedal posture and cannot easily withstand repeated strain imposed by oversize limbs.

youdao

事实上他们已经造出100多只了，另外还有两只，一只有很短的四肢，一只长着腊肠犬一样的尾巴。

They've produced more than 100 of them actually, as well as a mouse with short limbs and one with a tail like a dachshund.

youdao

实际上，两足动物的行走可能比四肢的行走花费更少的力气。

Walking as bipeds might actually use less energy than movement on all fours does.

youdao