题型:完形填空 完形填空 Can you swim? Do you like swimming? Yes? Well, how can you learn to swim? I think thebest way is to go into the water and learn. I'm afraid you'll 1 learn to swim just by readingbooks about swimming or 2 others swimming . It's 3 the English study for us kids today.We must practice, practice, and practice. Listening and speaking are very important for beginners. The children in 4 countries firstlisten to others. Then they try to imitate(模仿) and speak. We can listen to English programs 5 the radio. You may just understand 6 words. It doesn't matter. Just be 7 , try to getthe main topics, then the main ideas, then the key words, then the main sentences, 8 . As forspeaking , speak 9 . Reading and writing are more important for school students . First we must choose the bookswe are 10 . A lot of reading will 11 your language sense. This is the most important. Keep 12 English diaries. We can also write English articles. We may even post them 13 English magazines. Don't be afraid of failure. Failure is the mother of 14 . Easier said than done. Well, let's do more practice from now on. I'm sure you'll learn Englishwell 15 this way.( )1. A. just ( )2. A. Look at ( )3. A. same as ( )4. A. speaking-English ( )5. A. in ( )6. A. a little ( )7. A. relaxed ( )8. A. the full means ( )9. A. as many as you can( )10. A. interested ( )11. A. change ( )12. A. to write ( )13. A. for ( )14. A. succeed ( )15. A. usingB. never B. looking at B. different to B. English-speaking B. over B. a few B. relaxing B. the full meaning B. as more as you canB. interesting B. develop B. write B. to B. success B. inC. yet C. seeing C. the same as C. spoken English C. from C. few C. relax C. the full meanings C. as much as possibleC. interested in C. improve C. writing C. till C. successful C. by 查看答案
题型:单项选择题 若在数据库设计过程中,将关系模式R<U,F>分解为关系模式R1<U1,F1>,R2<U2,F2>,…,Rn<Un,Fn>。下列关于模式分解的叙述中,哪些条是正确的( ) Ⅰ.模式分解具有无损连接性的含义是:若对于R的任何一个可能取值r,都有r在R1,R2,…,Rn上的投影的自然连接等于r Ⅱ.模式分解保持函数依赖的含义是:F所逻辑蕴含的函数依赖一定也由分解得到的各个关系模式中的函数依赖所逻辑蕴含 Ⅲ.若一个模式分解具有无损连接性,则该分解一定保持函数依赖 Ⅳ.若一个模式分解保持函数依赖,则该分解一定具有无损连接性 ∨.模式分解可以做到既具有无损连接性,又保持函数依赖 Ⅵ.模式分解不可能做到既具有无损连接性,又保持函数依赖A.仅Ⅰ、Ⅱ和∨B.仅Ⅰ、Ⅱ和ⅥC.仅Ⅰ和ⅢD.仅Ⅱ和Ⅳ 查看答案