每一个生态系统都与周围的其他生态系统相关联，这种关联性表现在方方面面。例如，我们的母亲河——长江和黄河，作为____ 生态系统，源自西部源头的____ 生态系统、____ 生态系统。河水奔流东去，滋润着沿途的____ 生态系统，养育着亿万人口和其他生物。它们沿途还形成____ 生态系统、____ 生态系统，最终夹裹着陆地上的土壤和其他物质，融入____ 生态系统。

用一根60厘米长的铁丝焊成一个正方体，这个正方体的表面积是____平方厘米，体积是____立方厘米。

    Chores weren't popular at my house. My children didn't like to do chores. They always saw me do chores, but they hardly ever helped me do them.

    A year ago, I made a game called "The Endless Chore Game". It's really great. Here show the game works.

    I make a card with forty squares（方框）, and I writea different chore on each square. These chores can be easy and interesting like making dessert. Then my family roll the dice（骰子）to decide what chores we have to do. The card also has a few squares with fun things, like watching TV and singing. If you're lucky, you can watch TV when the others are doing the chores.

    My son likes the game very much. He goes to the kitchen happily every morning to do the game. It's really a good way to make my children do chores. You can have a try if you have the same problem as me.