题目

去甲肾上腺素是一种常见的神经递质，该神经递质能使突触后膜产生兴奋，但是当去甲肾上腺素分泌较多时又可以作用于突触前膜，抑制去甲肾上腺素的释放。据此判断，下列说法中不正确的是( )A. 突触前膜和突触后膜都有与去甲肾上腺素结合的受体B. 去甲肾上腺素与不同的受体结合后产生的效应是相同的C. 去甲肾上腺素分泌过多作用于突触前膜属于反馈调节D. 突触间隙中的去甲肾上腺素能在一定的浓度范围维持相对稳定We all need to exercise. Doctors say it is good for us. It makes your heart and body strong. Children who often exercise are more alert (灵活). This means( 意思是) they do better in tests and schoolwork than those who don’t exercise.There are many ways to exercise. You can walk, run, swim, skate, or play ball games. Make sure you exercise in the following ways. You have to like what you’re doing. Exercise enough---but not too much. It’s best to exercise twice a week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or even three sports that feel right for you.You can exercise at fitness centers. There are a lot of equipment (设备) there. The equipment will help you to exercise your arms, legs, and other parts of your body to make you fit. Some people buy equipment. But it is very expensive.Exercising can be fun. Friends can exercise together at a fitness center or they can play sports together. How do you exercise?1.In the text, the writer tells us that we need to _____.A. drink B. sleepC. exercise D. work2.The sentence “Children who often exercise are more alert” tells us that people who often exercise can do better in _____.A. running B. skatingC. swimming D. studies3.Which of the following sports is NOT mentioned (提到) in the text?A. Fishing. B. Running.C. Swimming. D. Walking.4.The words “fitness centers” in the text mean _____.A.商务中心 B.健身中心C.购物中心 D.医疗中心5. Exercising can be fun, because _____.A. it makes your heart and body strongB. it makes you study betterC. people can buy equipment for their homeD. friends can play sports together