问题
填空题
用弹簧测力计测出一个铁块的重力G，再把铁块浸入水中，读出弹簧测力计的示数为F，则铁块在水中受到的浮力为______．
答案
铁块在水中受到竖直向下的重力G、竖直向上的拉力F、竖直向上的浮力F浮作用而静止，
铁块处于平衡状态，由平衡条件得：G=F浮+F，则F浮=G-F；
故答案为：G-F．
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用弹簧测力计测出一个铁块的重力G，再把铁块浸入水中，读出弹簧测力计的示数为F，则铁块在水中受到的浮力为______．
铁块在水中受到竖直向下的重力G、竖直向上的拉力F、竖直向上的浮力F浮作用而静止，
铁块处于平衡状态，由平衡条件得：G=F浮+F，则F浮=G-F；
故答案为：G-F．
根据短文内容，从下框A~F选项中选出能概括每段主题的最佳选项，并在答题卡上将该选项涂黑。选项中有一项为多余项。
As awareness of the benefits of humour increases, most of us want to get all the laughs we can. It seems that almost every day there is another new discovery about the power of humour to help us physically, mentally, emotionally, and spiritually. Every system of the body responds to laughter in some important or positive way . 65.________ Many people mistakenly believe that we are born with a sense of humour. They think that when it comes to a sense of humour. “either you have got it or you don't . ” This is false! What is true, however, is that the ability to laugh and smile is actually something we are born with. For example, we laugh when we are tickled under the arm, even without thinking about how to react. 66._________ The parts of the brain and central nervous system that control laughing and smiling are mature at birth in human infants, but that is not the same thing as having a sense of humour. (After all, when a baby laughs in his small bed we don’t rush over and say, “That kid has a great sense of humour!”) Your sense of humour is something you can develop over a lifetime. Don’t be nervous before others and try to laugh at yourself-then you will make them laugh too. 67.________ Humour includes a lot more than laughing and joke telling. Many people worry needlessly that they do not have a good sense of humour because they are not good joke tellers. More than jokes, a sense of humour requires being willing and able to see the funny side of life’s situations as they happen. In fact, one of the best definitions（定义）of a sense of humour is “the ability to see the nonserious element in a situation. ” 68. _________ There may be a thousand different ways to express your sense of humour, but joke telling is only one of those ways. As more is discovered about how humour benefits our life, more people will be able to see and enjoy the humour when they are in a difficult situation. Life depends on air, food and water, but it is made easier to live with a good sense of humour. |