长期的自然选择，使生物在形态、结构、功能等各个方面都表现出适应性。如与静脉相比，人体四肢的动脉一般分布在较深的地方，这是对下列何者的适应(     )

我当小裁判。

    There is a zoo in our city. It's very big. In the zoo, there are many animals. Look, the birds are singing in the tree. A bear is riding（骑）a bike. A tiger is eating meat（肉）. Two monkeys are climbing(爬）a tree. They are happy in the zoo. 

阅读短文，判断正误。