阅读下面材料， 在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

    Jenny began to go to school when she was at the age of six. She liked her ____ (one) day very much. Her teacher, Miss Black, ____ (be) very nice, too.

    At the end of the second day, the other children ____ (leave) the classroom after school but Jenny stayed behind and waited. At first, Miss Black had some work to do and ____ (not) see Jenny, but then she looked up and saw her.

    "Why not go with the ____ (other), Jenny?" she asked her kindly. "Do you want ____ (ask) me any questions?"

    "Yes. Miss Black," Jenny said.

    "____ is it?" Miss Black asked.

    "What did I do in school today?" Jenny said.

    Miss Black laughed. "What did you do in school today?" she said. "Why did you ask ____ (I) that, Jenny?"

    "____ I'm going home now," Jenny answered, "and my mother ____ (would) ask me."

我国劳动人民创造了‘桑基鱼塘”生态农业。随着科学技术的进步．将蚕沙、人畜粪便、桔杆、杂草、树叶等投入沼气他内发酵．制成沼气作燃料．然后再用沼气渣喂鱼。这样，就把传统的“桑、蚕、鱼”，农业结构，变成了‘桑、蚕、气，鱼”的新型农业结构，如图所示。

（1）此生态系统中属于非生物部分的是____ 等。
(2）此生态系统中能产生沼气的腐生细菌属于____ 。
(3）若某种难分解有毒物质进入该生态系统后．体内有毒物质积累最多的是____ 。
(4）写出该生态系统中的一条食物链：____ 。

关于绕地球做匀速圆周运动的人造卫星，下列说法中正确的是（　　）

下列曲线图能正确表达相应反应或过程的是（   ）