梯形的面积一定比平行四边形的面积小．______．（判断对错）
可以用举例法证明：
设梯形的上底为10厘米，下底为20厘米，高为10厘米，平行四边形的底为8厘米，高为8厘米，高为2厘米，
梯形的面积为：（10+20）×10÷2
=30×10÷2，
=300÷2，
=150（平方厘米），
平行四边形的面积为：8×2=16（平方厘米）；
所以题干中没有相应的数据所以不能判断梯形的面积和平行四边形的面积之间的大小关系；
故答案为：错．
完型填空（15分） I have had thousands of classes since I started school nine years ago. But only one _1_ was the most important. It happened last term just after I had got a _2_ result in an exam. I was sad and had lost my confidence. I decided to go to a class which can tell me how to be_3_. The speaker walked into the room. But he did not start talking _4_ a teacher. Instead, he held up a twenty Yuan note(钞票)! “Who wants this?” he asked. Unsurprisingly, _5_ of us in the class held up our hands. The speaker smiled. Then he put up the note on the blackboard and asked the same question. Again, we all put up our hands. The speaker smiled again, but _6_nothing. Suddenly, he threw the note onto the floor! Then he asked the same _7_ a third time. I didn’t _8_ what the speaker was doing. Why was he asking the same question again and again? I didn’t know what to do. I wanted the note, _9_ I put my hand up again. After a while, he _10_ the note and started to laugh. “You have all just told me how to become successful,” _11_ said to us with the note in his hand. “The note is worth twenty yuan. It is _12_ worth twenty yuan, even though I throw it on the floor. You are like the note. No matter _13_ happens to you, you still have your worth.” When I heard those words, I was deeply moved. Suddenly, I _14_ I was worth a lot. I may have done badly in an exam, but it doesn’t _15_ I can’t do well in the future. If I believe in myself, I will be successful!
|