如图是一个封闭的养鱼缸，有水（25度）、鱼、金鱼藻、缸底的河泥，阳光照射进缸内，构成一个稳定的生态系统，请思考以下问题：

（1）各类生物数量和所占的比例能保持相对稳定，说明生态系统有一的____ 

（2）金鱼藻属于生态系统的____ 者，它能进行光合作用，将____ 能转化为____ 能储存在制造的有机物中．

（3）____ 能将金鱼藻的粪便分解为简单的无机物．

以下向量中，能成为以行列式形式表示的直线方程$\left|\begin{array}{ccc}1& 0& 1\\ x& 2& 1\\ y& 1& 1\end{array}\right|$=0的一个法向量的是（　　）

水蒸气达到饱和时，水蒸气的压强不再变化，这时(  )

完形填空,阅读下面的短文，从短文后各题所给的选项中选出能填入空白处的最佳答案。

Bees live in a house that is called a hive. There are three kinds of bees: workers, drones (雄蜂) 1queens. Only one queen bee can live in each hive. If she is lost or dead, the other bees 2 their work.

Workers are very clever and busy. They all join together3 small rooms called cells of wax for their honey. Each worker bee does its own work. Some go out and collect honey from the flowers; 4 stay at home and work inside the hive. The cells5have six sides are made by worker bees. Did you ever look into a glass hive and see them while at work? It is 6to see how busy they always are. Before winter comes, all the drones are driven from the hive7 they don’t eat the honey they did not collect.

It is not safe 8 children to be too close to bees. Bees have painful stings they use in their defense (防御).

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