动物的先天性行为所具备的特点是（ ）

阅读下文，回答问题

拾贝壳

      我一向喜欢贝壳，吵着要阿姨带我去拾贝壳，阿姨答应了。

      我们来到海边，啊，这里的景色真美，浪花轻轻拍打着海岸，发出“哗哗哗“的响声；蓝色的海面上航行着小小的帆船和”突突突“的汽艇。我望着无边无际的大海，心情十分舒畅。

      在海滩上，我们卷起裤管，俯下身子，拾起贝壳来。这里到处是五颜六色的贝壳：有大的、小的、尖的、圆的、扁的、各种形状、各种色泽，真实千奇百怪。它们在阳光下闪闪发光。忽然，阿姨叫道：“小红，快来，这个贝壳多好看！“我跑过去一看，果真是一个好贝壳，它有小碗那么大，身上印着一条一条棕色花纹，和老虎身上的花纹一样。我急忙接过来，掏出手帕，小心翼翼地把它包好。

      渐渐地，小篮子装满了贝壳，我们高高兴兴地准备回家。离开海滩时，我不时回过头去，啊！我爱美丽的贝壳，我爱金色的沙滩，我更爱祖国蓝色的海洋！

They _____ young then. （  ）

    Our school is a green school．What makes it green？

    First，we have a lot of trees．There are trees in front of and behind every building．Some trees are green only in spring and summer．And some are green all year round．The trees make our school look like a big forest.

    And our school is a green one because we "go green". How do we go green？We have two green days every month．On green days，no students or teachers go to school by car．And we have clean﹣up Day every month．That day，students go to streets to pick up rubbish．Also，we have tree﹣planting Day every spring．We plant young trees on hills．We have three green clubs The members of the clubs look after those trees well．

    Green is not only a colour．It is about life．Please go green with us and make the world a more beautiful place．