题干

如题图所示,考古人员需要对一口古井进行清理,为了解决照明问题,请你帮助他们利用一块平面镜将太阳光反射到井里,并能垂直照亮井底。(保留必要的作图痕迹)


上一题 下一题 0.0难度 选择题 更新时间:2018-12-25 07:41:41

答案(点此获取答案解析)

解:如图所示:

同类题4

阅读理解

    For some students, getting better grades can seem like an impossible task sometimes. With the challenges(挑战) of school, just paying attention in class or studying hard isn't always enough. But what if there were other ways for students to improve their grades? For parents and students who have ever wondered if this is possible, now you can rest easy. Research suggests that a person who likes doing activities can improve their grades.

    Scientists think that those students who are active are not just exercising their bodies, but also exercising their brains(大脑). In turn, they can be able to improve their grades at school.

    In the most recent study, researchers found that when children played for half an hour each day, they were better at organizing(组织) their schoolwork as well as doing project work and learning traditionally “difficult” subjects, such as maths.

    What does this mean for children who aren't active? Researchers think that if kids don't get enough activities, they are going to be at a disadvantage when it comes to school performance.

    In the research experiment, a group of children skipped with ropes(跳绳), played basketball and did a number of other games or exercises. Another group of children didn't do any activities. They took part in testing both before experiment and after the experiment. Testing was mainly for maths and reading skills. Results showed that the children in the activity group did better on the tests than those who had no activity.

    All work and no play will not only make Jack a dull(迟钝的) boy, but will also negatively(消极地) affect his grades in school, according to a new study published in the Journal of Pediatrics.

    Parents complain(抱怨) children today are actually less active and they always worry about their grades. Dr. Belton, an expert, said, “If you'd like to see your kids do better in school, have them close their books, set down their pencils and go outside to play.”