问题
选择题
若x2+3x+5=7，则代数式3x2+9x-11的值为（ ）
A．5
B．-6
C．7
D．-5
答案
∵x2+3x+5=7，
∴x2+3x=2．
∴3x2+9x-11=3（x2+3x）-11=6-11=-5．
故选D．
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若x2+3x+5=7，则代数式3x2+9x-11的值为（ ）
A．5
B．-6
C．7
D．-5
∵x2+3x+5=7，
∴x2+3x=2．
∴3x2+9x-11=3（x2+3x）-11=6-11=-5．
故选D．
| 完型填空： | ||||
| The Chinese diet is considered（认为）to be the healthiest in the world. It contains a lot of fruit and green ___1___. It is rich in fibre and ___2___in sugar and fat. The Chinese eat less sugar than people in many other ___3___in the world. That is why lots of people in China have healthy white ___4___. People in the Western world do not eat such healthy foods. They eat too ___5___ fat and sugar and don’t take ___6___exercise. Because of this, they put on weight very ___7___. Their diet contains a lot of fat in the form of potato crisps, potato chips, butter, cream and chocolate. They ___8___a lot of sugar in the form of cakes, soft drinks, sweets and so on. The ___9___is that many of them become fat. And some have bad teeth. In some ___10___of Britain, one person in ten, by the age of thirty, has no teeth left! | ||||
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| 完形填空。 | ||||
| Jane 1 her bedroom because she likes sleeping (睡觉). Michael likes the 2 room best for he often watches TV and does many things there. Kangkang likes the dining room because she likes 3 . They are all my good friends. 4 Sundays they often come to my home. I 5 a dining room. 6 a round table and four 7 in it. We eat meals and drink 8 and talk 9 English. 10 there any dining rooms in your house? | ||||
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