阅读理解。 Giving your child a chocolate bar for him to finish his maths homework is an excellent idea, according to researchers who claim that the yummy treat could improve the brain's ability to do the most 'dreadful' subject. The study, presented at the British Psychological Society annual conference, is great news for students who binge on(暴食) chocolate when revising for exams. For the study 30 voluhteers were asked to count backwards in groups of three from a random number between 800 and 999 generated by a computer. The findings show that they could do the calculations more quickly and more accurately after they had been given the cocoa drink. However,the same was not true when the group was asked to count backwards in groups of seven, which the researchers described as a more complex task, requiring a slightly different part of the brain. The findings also show that the volunteers did not get as tired doing the calculations if they bad heen given the cocoa drink despite being asked to do them over and over for an hour. The flavanols (黄烷醇) work by increasing the flow of blood into the brain. Dark chocolate contains higher quantifies of the chemical than plain or milk chocolate. Prof. David Kennedy at Northumbria University said that chocolate could be beneficial for mentally challenging tasks. The researchers gave the volunteers a total of 500 mg of flavanol. Although the amount was too great to be found naturally in the diet, researchers said that people should ensure that they have lots of flavanols. 'The more fruit and vegetables and things that are high in flavanols, the better that is for your brain in the long run.' 1. The researchers tend to think that _____. A. chocolate is good for children's health B. delicious food improves the brain's ability C. maths is difficult for children to learn D. all students like eating chocolate for exams 2. How did the volunteers' calculations get improved after the drink? A. Hot drink helps students operate computers fasten. B. Hot drink is likely to speed up the brain's activity. C. The flavanols help more blood flow into the brain. D. The flavanols are chemicals that make people relaxed. 3. Which of the following contains the most flavanols? A. Dark chocolate. B. Plain chocolate. C. Milk chocolate. D. Fruit. 4. It can be concluded from the last paragraph that _____. A. flavanols can help solve more complex problems B. lower doses of flavanol have no effect on the brain C. people should eat more vegetables instead of chocolate D. students should have enough flavanols in the daily diet