1、第第2626章章二次函数二次函数3.3.实践与探索实践与探索 知知 识识 管管 理理 学学 习习 指指 南南 归归 类类 探探 究究 当当 堂堂 测测 评评 分分 层层 作作 业业 第第1课时二次函数与一元二次方程、一元二次不等式的关系课时二次函数与一元二次方程、一元二次不等式的关系学学 习习 指指 南南 知知 识识 管管 理理有两个交点 有一个交点 没有交点 有两个不相等的实数根 有两个相等的实数根 没有实数根 归归 类类 探探 究究 B 当当 堂堂 测测 评评 A C yx22x 1或3 x0或x2 0 x2 分分 层层 作作 业业B D (2，0)(3，0)x1或x4 D D 全文结束！
2、再见全文结束！再见o study whether experiences during teen years would influence adult health.So they followed 171 teens,starting when the kids were just 13.They interviewed each one every year for five years，and also spoke to these teens closest friends，who provided additional information about the quality o
3、f their friendships.The same 171 people were interviewed again at ages 25,26 and 27.This time,the questions surveyed each persons overall health.When the researchers analyzed the data,they found a strong connection between a teens behavior and adult health.Teens who had close friends grew up to be t
4、he healthier adults.Whether teens held back their feelings or expressed them to close friends also influenced later health.Those who held back their feelings were more likely to be sick as adults.The connection held up even after the scientists accounted for other possible influences on health.Weigh
5、t，family income and drug use were all examined.So were mental health issues，such as anxiety and depression.And in these people，such other factors did not explain adult health as well as teen friendships did.Getting along with the crowd may have benefits,says Allen,but there are also drawbacks.Teens
6、who are more independent tend to do better at school and work.And peer pressure may lead some kids to engage in risky behavior,such as smoking,drinking or using drugs.Dealing with it is an ongoing challenge，Allen acknowledges.“Finding the right balance is the key.Teens shouldnt lose heart for not finding this easy.”And,he adds，“Parents need to be understanding about the pressures teens face.”
