题目

若一个直三棱柱的所有棱长都为1，且其顶点都在一个球面上，则该球的表面积为（ ）．A. B. C. D. 答案：【答案】B【解析】根据题意画出其立体图形.设此直三棱柱两底面的中心分别为,则球心为线段的中点,利用勾股定理求出球的半径,即可求得该球的表面积．画出其立体图形: 直三棱柱的所有棱长都为1,且每个顶点都在球的球面上，设此直三棱柱两底面的中心分别为,则球心为线段的中点，设球的半径为，在 第二节（共5小题，每小题2分，满分10分。本部分答案请用签字笔写在第二卷规定的位置。） 根据文章内容， 从下列A-F选项中选出能概括每一段主题的最佳选项，选项中有一项为多余。 A.Wash yourself as often as possible B.Avoid being in hot sun C.Keep away from smoke and alcohol D.The importance of skin E.Have a balanced diet F.Be sure to have enough water 41. __________ When it comes to your skin, there is an important fact that you must keep in mind: Your skin is the largest organ of your body. Therefore, skin health and protection is crucial. Your skin does everything for you. It can keep your body hydrated and regulate your body’s temperature. Now, here are some helpful tips for you to protect your skin:  42.__________ Protection against harmful rays from the sun is one of the most important steps that you need to take. With this in mind it is necessary for you to avoid strong sunlight as often as possible. As for sunscreen you need to buy products that contain UVA-1, UVA-2 and UVB protectiion.  43___________ Your diet also has a direct impact on the health of your skin. The most important aspect of your diet in relation to the health of your skin is to make certain that you eat a proper amount of food items that contain the proteins and nutrients necessary for cellular maintenance, repair and regeneration. 44.__________  Water is also important to the health of your skin. While you cerrtainly have heard it before, it actually is true that you should drink at least eight 8-ounce glasses of fresh water every day. There are many health benefits to be derived from drinking water daily, including maintaining healthy skin. 45__________ Finally, when it comes to the health of your skin today and into the future you should avoid smoking all together.In addition, you should drink alcohol only in moderation. Both smoking and excessive alcohol consumption can negatively impact the health of your skin in significant ways.