地球上最大的生态系统是海洋生态系统．

下列4种生物中，细胞结构与其它3种生物有明显区别的是（  ）

下列天体系统中，层次最低的是（　　）

根据短文内容，选择正确答案。  

    Here is a photo. The two girls have big blue eyes and long brown hair. They are both ten years old. They are in the same class. The one in a yellow skirt is Lily. The other one (另一个) an orange skirt is Lucy. Their father (父亲) is Mr. White. He is in a brown coat. Their mom is Mrs. White. She is in a black dress. Who is that boy in a blue cap? He is Lucy and Lily's brother(哥哥), Bob. He is a high school student. Look! Lucy and Lily are in a green car.

如图是一个数值转换机，若输入的x为﹣5，则输出的结果是____ ．