用括号内所给单词的适当形式填空,必要时可加助动词或情态动词。
Waste can be seen everywhere in our school. Some students ask for more food than they can eat and others often forget____ (turn)off the lights when they leave the classroom. They say they can afford these things. But I____ (not agree)with them.Waste can bring a lot of problems. Although China is rich in some resources (资源), we're short of others, for example, fresh water(淡水). It____ (report) that we will have no coal(煤) or oil to use in 100 years. So if we go on____ (waste) our resources,what can we use in the future? Think about it. I think we should
say to the students who waste things every day. Everybody____ (stop) wasting as soon as possible.
In our everyday life, we can do many things____ (prevent) waste from happening, turn off the water taps(龙头) when we____ (finish) washing, turn off the lights when we leave the classroom, try not to order more food than we need, and so on. Little by little, everything will be changed. Waste can be stopped one day if we do our best.

实验室常用的弹簧秤如图甲所示，连接有挂钩的拉杆与弹簧相连，并固定在外壳一端，外壳上固定一个圆环，可以认为弹簧秤的总质量主要集中在外壳（重力为G）上，弹簧和拉杆的质量忽略不计．现将该弹簧秤以两种方式固定于地面上，如图乙、丙所示，分别用恒力F₀竖直向上拉弹簧秤，静止时（   ）

专题与实践。