题干

如图表示在最适温度下,反应物浓度对酶所催化的化学反应速率的影响.据图分析,错误的是(    )

A:如果A点时温度升高10℃,会使反应速率下降

B:在B点时,反应物浓度限制了反应速率的提高

C:如果在C点时加入少量的酶,会使反应速率加快

D:A~B段,随着反应物浓度的增加,反应速率加快

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B

同类题1

完形填空。

    It was the end of the week at the village school. The bell had rung, and the children had run out into the bright sunshine, wild with laughter and fun. All were happy but poor Davy. He came out last and very1. He was in trouble, and the bright, golden sunlight did not make him2. He walked across the yard, and sat down on a stone behind the old maple. A little bird on the highest branch sang just to make him3. But Davy did not notice it. He was thinking of the4words that had been said about his ragged clothes. The5stole out of his eyes, and ran down his cheeks. Poor little Davy had no6, and his mother had to work hard to keep him at school all by herself. He did not wish to trouble his mother; so he 7among the trees , and at last threw himself on the green moss under them. Just then his beloved teacher Mrs. Smith came8. She saw who it was, smith stopped to ask what was the9 . Davy did not speak, but the tears began to start. Mrs. Smith waited patiently10Davy told her all his  trouble. When he ended, she said11, “Davy. I have a plan which I think will help you.” “Oh , what is it ?” He said, sitting up with a look of 12while a tear fell upon a blue violet. “Well, how would you like to be a little flower13? And earn money?” “That would be jolly. But where shall I get my flowers?” he asked. “14, my boy, the answer to the question is just right in there15.” said Mrs. Smith. “Here are lively blue violets, down by the brook are white ones, and among the rocks are ferns and mosses. 16them all to my house, and I will help you17them.” Davy nodded and went home happily. Day after day. Davy hunted the woods for the18flowers, and the most beautiful ferns and mosses. After his teacher had helped him with new clothes. But for the19, and sold them. He soon carted enough money to buy new clothes. But for the20of his teacher, he couldn't have solved his problem. Now he could see the bright sunshine and hear the bird's singing.

同类题5

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     Parents are creating an “I want it now” generation by indulging children’s every demand at Christmas,say experts.Youngsters are becoming increasingly selfish,claim the education analysts.

     Consumer­savvy children are forcing their families into racking up huge debts and risk becoming spoilt and dissatisfied in the future.

     Behavioural consultant Chris Calland said,“Parents are desperate to make Christmas into a magical fairy tale for their kids.There’s nothing wrong with that as such.The problem arises when it means always giving into all our children’s demands—even if they are beyond our price range or not age­appropriate.”

     Ms Calland,who runs “Santa Says No”  style sessions with  colleague Nicky Hutchinson,added,“Many of us go into so much debt providing the gifts our children want that we spend the rest of the year paying off the bills.Yet so often the parcels we’ve carefully wrapped,once opened,are just pushed away because the very thing our little boy or girl was once so desperate for,they have now lost interest in.”

     Ms Calland and Ms Hutchinson have drawn up a list of guidelines to help pare nts manage their offspring’s Christmas lists this year.They say that adults can actually improve their relationships with their children by resisting “pester (纠缠) power”.

     Ms Calland said,“All too often we say yes because we want an easier life when the fact is that we’re only building up problems for the future.We are helping create a generation of youngsters who are blind to the needs of others and the necessity of hard work.”               

   “Children learn fast—if we sometimes change our mind,they quickly realise it might be worth lying on the floor and screaming for it.Make sure you and your partner are working together on this.Be consistent.And try not to get caught up in competition with other families or friends.”