陈时

研究发现，坚持一项规律的、高强度的体育锻炼活动，能够帮助学生提高学习成绩。经常参加体育锻炼的孩子往往在英语、数学、科学这三门课上有更好的表现。

1. accelerometer /？藜k？謣sel？藜？謖r？鬑m？奘t？藜（r）/ n. 加速度计

2. certificate /s？藜？謖t？奘f？奘k？藜t/ n. 合格证书;证明

Teenagers who routinely engaged in moderate and energetic exercise have long？鄄term improvements in their academic performance， a new study suggests.

The researchers looked at a sample of about 5，000 children who were enrolled in a long？鄄running study that tracks children born in the UK between 1991 and 1992. When children reached 11 years old， their daily physical activity levels were measured using an accelerometer  for three to seven days. The device， similar to how a pedometer tracks steps， recorded the average time children exercised， which was 29 minutes a day for boys and 18 minutes for girls.

The actual levels of daily physical activity at age 11 were quite low. The children had their academic performance tested at ages 11 and 13 with compulsory national tests for students， and also at 15 or 16 with the General Certificate of Secondary Education （GCSE） exam. The tests judged the children？蒺s abilities in English， math and science subjects.

When factors that could affect academic performance including birth weight， mother？蒺s age at delivery and other socioeconomic factors were adjusted for， the results showed that the more children participated in moderate and energetic physical activity， the higher their test scores were at age 11 in all three subjects. For girls， science scores were most strongly linked to exercise. When they followed up with the kids at age 13， their academic scores were still linked to how much they exercised when they were 11 years old.

By the time the kids took the GCSE exam， each 17？鄄minute per day increase in physical activity for the boys was linked to an improvement in their scores. Every additional 12？鄄minutes a day increase in exercise for the girls was linked to an increased score as well， especially in the science category.

The researchers concluded that this study could show that there are gender differences in how exercise affects the brain. They also called for more studies to look at academic benefits that could be gained if students exercise the recommended 60 minutes or more a day.

1. How did the researchers carry out the study？

A. By asking different questions.

B. By using tracking equipment.

C. By asking teens to take some tests.

D. By asking teens to report the exercise time.

2. According to the passage， what can affect a teen？蒺s academic performance？

A. His age. B. His birth date.

C. His mother？蒺s weight. D. His mother？蒺s age at delivery.

3. According to the researches， how long should the students exercise per day？

A. 12 minutes. B. 18 minutes. C. Half an hour. D. One hour.

Difficult sentence

When children reached 11 years old， their daily physical activity levels were measured using an accelerometer for three to seven days.

【翻譯】

【点石成金】本句是一个主从复合句。When引导时间状语从句，主句的主语是their daily physical activity levels，using an accelerometer...是现在分词作伴随状语。