...a human being should not behave like a donkey.
...a human being should forever strive for a better life.
...a human being should not give up under harsh conditions.
...a human being should be physically stronger than a donkey.
句意：一头驴可以让自己被压倒，但是人不能，人是上帝创造的最优秀的成果。A项：人类是最高的动物形式，从不因为艰苦奋斗而让自己倒下。符合句意。
