矿井通风系统是指风流由（）进入矿井，经过井下各用风场所，然后从（）排出，风流流经的整 发布时间：2017-05-14 03:50 │ 来源：www.tikuol.com 题型：填空题 问题： 矿井通风系统是指风流由（）进入矿井，经过井下各用风场所，然后从（）排出，风流流经的整个路线及其配套的通风设施称为矿井通风系统。
题型：填空题 完形填空。 The requirements for high school graduation have just changed in my community. As a result, all studentsmust 1 sixty hours of service learning, 2 they will not receive a diploma. Service learning is academiclearning that also helps the community. 3 of service learning include cleaning up a polluted river, working in a soup kitchen, or tutoring a student. 4 a service experience, students must keep a journal (日志) and then write a 5 about what they have learned. Supporters claim that there are many 6 of service learning. Perhaps most importantly, students are forced to think 7 their own interests and become 8 of the needs of others. Students are also able to learn real-life skills that 9 responsibility, problem-solving, and working as part of a team. 10 , students can explore possiblecareers 11 service learning. For example, if a student wonders what teaching is like, he or she can choose to work in an elementaryschool classroom a few afternoons each month. 12 there are many benefits, opponents (反对者) 13 problemswith the new requirement. First, they 14 that the main reason students go to school is to learn core subjects and skills. Because service learning is time-consuming, students spend 15 time studying the core subjects. Second, they believe that forcing students to work without 16 goes against the law. By requiring service, the school takes away an individual's freedom to choose. In my view, service learning is a great way to 17 to the community, learn new skills, and explore differentcareers. 18 , I don' t believe you should force people to help others-the 19 to help must come from the heart. I think the best 20 is one that gives students choices: a student should be able to choose sixty hours of independent study or sixty hours of service. Choice encourages both freedom and responsibility, and as young adults, we must learn to handle both wisely. ( )1. A. spend ( )2. A. and ( )3. A. Subjects ( )4. A. With ( )5. A. diary ( )6. A. courses ( )7. A. beyond ( )8. A. careful ( )9. A. possess ( )10. A. Gradually ( )11. A. through ( )12. A. So ( )13. A. deal with ( )14. A. argue ( )15. A. much ( )16. A. cost ( )17. A. contribute ( )18. A. Therefore ( )19. A. courage ( )20. A. decision B. gain B. or B. ideas B. Before B. report B. benefits B. about B. proud B. apply B. Finally B. across B. Thus B. look into B. doubt B. full B. pay B. appeal B. Otherwise B. desire B. purpose C. complete C. but C. Procedures C. During C. note C. challenges C. over C. tired C. include C. Luckily C. of C. Since C. point out C. overlook C. less C. care. C. attend C. Besides C. emotion C. solution D. save D. for D. Examples D. After D. notice D. features D. in D. aware D. develop D. Hopefully D. on D. While D. take down D. admit D. more D. praise D. belong D. However D. spirit D. result 查看答案
题型：填空题 构成投资组合的证券甲和证券乙，其标准差分别为12%和8%。在等比例投资的情况下，如果两种证券的相关系数为1，该组合的标准差为10%；如果两种证券的相关系数为-1，则该组合的标准差为2%。 ( ) 查看答案