题目

某同学想通过实验来探究“影响滑轮组的机械效率的因素”．他做了如图所示的实验，并测算了各次实验装置的机械效率．关于他的实验过程，下列说法中不正确的是A. 根据①、②两次实验可知：滑轮组的机械效率与绳子的绕法无关B. 根据②、③两次实验可知：同一滑轮组提起物重越大，机械效率越低C. 根据该同学的探究结论可知，通过适当增大物重可以提高滑轮组的机械效率D. 为使实验的结论更具可靠性，应换用不同的装置进行多次实验归纳得出普The high school years are a key period. The things we learn during this time really shape our lives. Liu Changrning, principal of Beijing No. 4 High School made 18 suggestions for students just starting high school on how to get the best out of high school. Here are ten of them. 1) Read 50 books. But choose them from ten different fields. 2) Help a person. Look for a classmate, an elderly person, in fact anyone who could benefit (获益) from your help. You'll find you benefit too! 3) Research. Research a particular area, such as science, history or art. 4) Make a foreign friend. Try to be friend someone from a foreign country. It's an ideal way to learn about a foreign country. 5) Publish (出版) an article. Whether it appears in a newspaper, your school magazine or in your own blog, an article will be something to look back on in pride in later years. 6) Take up a new sport. Choose one you've never played before. If you find you like it, you'll have a hobby for life.7) Join a club. Working hard in a club or other activities will give you a life outside of your studies. 8) Find a part-time job. Try and do the job for at least a month. 9) Find a person to learn from. Choose someone with unusual experience or special talent. Try to learn all you can from him or her. 10) Learn to cook four Chinese dishes. Learning how to cook is not only a practical skill but a way of building a bridge to other people1.According to the passage, by making a foreign friend you can______.A.learn about another cultureB.practice spoken EnglishC.discuss the international situationD.share your happiness and sadness2.Besides learning a practical skill, another purpose of learning to cook is______.A.to help your parents with houseworkB.to kill timeC.to have communication with othersD.to make friends3.Which of the following statements is True according to the passage?A.You should read fifty books of the same fieldB.Do a part-time job for less than a monthC.Try to publish an article to make you famousD.You can benefit a lot by helping others4.The principal made the suggestions in order for the students to______.A.make contributions to societyB.achieve great progress in high schoolC.love high school lifeD.finish high school