变电所接地网接地电阻的大小与（）无关。A、接地体的尺寸 B、土壤电阻率 C、地网面积 发布时间：2017-10-28 03:58 │ 来源：www.tikuol.com 题型：单项选择题 问题： 变电所接地网接地电阻的大小与（）无关。A、接地体的尺寸B、土壤电阻率C、地网面积D、电气设备的数量
题型：单项选择题 阅读理解。 Teeth are important. Strong , healthy teeth help you chew (咀嚼) foods that help you grow. They help you speak clearly. And yes, they help you look best. Here are some tips for you to take care of you teeth: 1. Brush your teeth the right way. Brush your teeth at least twice a day after breakfast and before bedtime. If you can, brush after lunch or after sweet snacks, too. Brush all of your teeth, not just the front ones. Spend time brushing teeth along the sides and back of your mouth. Spend at least three minutes each time you brush. Play a song you like to help pass the time. Get a new toothbrush every three months. When you buy toothbrush, be sure it has soft bristles (鬃毛). 2. Learn how to floss(用牙线剔牙) your teeth. Flossing is a very important way to keep your teeth healthy. Food may hide between two teeth. Flossing can help get rid of it. You'll need to floss your teeth at least once a day. 3. Have good eating habits. You need to be careful about what you eat and drink. Eating sugar is a major cause of tooth decay(蛀牙). Eat lots of fruits and vegetables and drink water instead of soda（苏打）. 1. How many times at least should we brush our teeth a day? ______[ ]A. 1 B. 2 C. 3 D. 42. What is the major cause of tooth decay? ______[ ]A. Not brushing teeth B. Not changing toothbrush C. Eating sugar D. Not flossing teeth 3. How often should we change our toothbrushes? ______[ ]A. never B. three times a month C. every three months D. every month4. The bristles of the toothbrush must be______[ ]A. hard B. soft C. expensive D. not mentioned5. Which is the right way to take care of teeth? ______[ ]A. Only brush front teeth. B. Not brush teeth before sleeping. C. Spend at most three minutes to brush teeth each time.D. Eat lots of fruits and vegetables and drink water instead of soda. 查看答案