问题 解答题

小刚在参观工厂时看到工人们把一些梯形模具加工成等腰梯形,检测时小刚发现,每个检测员根据产品及工具的具体情况,所采用的方法都不同,其中有两人用了以下的方法:检测员甲:测量上底中点到下底两端的距离,距离相等的就是合格的;测量员乙:测量下底中点到两腰的距离,距离相等的就是合格的.

小刚很快便明白了其中的道理,你能说出其中的道理吗?画出图形,并说明理由.

答案

(1)对于检测员甲的方法,如图①所示,

在梯形ABCD中,ADBC

∴∠AEB=∠EBC,∠DEC=∠ECB

∵EB=EC

∴∠EBC=∠ECB

∴∠AEB=∠DEC

又∵AE=DE,EB=EC

∴△AEB≌△DEC

∴AB=CD

即梯形ABCD是等腰梯形.

(2)对于检测员乙的方法,如答图②所示,

在梯形ABCD中,E为BC的中点,则BE=EC.

又∵EM⊥AB于M,EN⊥CD于N.

∴∠BME=90°,∠CNE=90°

∵EM=EN

∴Rt△BME≌Rt△CNE(HL)

∴∠B=∠C,即梯形ABCD是等腰梯形.

阅读理解

People are always afraid of making mistakes. But sometimes it’s not bad to make mistakes, and here is why.

At first, a mistake is a clear sign that you are trying new things. It’s always good to try new things, because when you are trying new things, you are growing. If you never try new things, how can you improve? How can you create? The simple answer is: “you can’t” Look around you, everything you see is the result of someone trying new things.

Another good thing about mistakes is this: when you are making mistakes, you are learning. For example, Edison failed 10,000 times before he invented the light bulb. When he was asked how he felt to fail that many times, he said that he hadn’t failed 10,000 times, but rather had learned 10,000 things that didn’t work.

Finally, when you make a mistake, you are much closer to success. Why? Because you have said what you should say, and you have done what you should do. Every time you make a mistake, you are closer to success. But it doesn’t mean that you can make mistakes without thinking. Instead, when you try new things you have to think them over, so that you can keep away from some unnecessary mistakes. We shouldn’t spend all our time and money on the only one way, but use them correctly, because our time and money are limited(有限的)

There is an old saying, “if you are not making mistakes, you are not trying hard enough.” So go bravely and make mistakes. And learn, and grow, and succeed.

小题1:If you are making a mistake, that means__________.

A.you’re careful

B.you’re kind

C.you’re growing

D.you know nothing小题2:If you never try new things, you can’t___________.

A.improve

B.create

C. spend

D.A and B小题3: After Edison failed 10,000 times, he__________.

A.gave up

B.invented the light bulb

C.invented the computer

D.invented 10,000 new things小题4:When you make a mistake, you are closer to___________.

A.time

B.money

C.success

D.new things小题5: What’s the main idea of the passage?

A.Never make mistakes

B.You can make mistakes without thinking

C.Sometimes it’s good to make mistakes

D.Making mistakes is terrible

填空题