题目

先化简，再求值：，其中． 答案：【答案】，2.【解析】试题原式利用除法法则变形，约分得到最简结果，将a与b的值代入计算即可求出值．试题解析：解：原式=.当时，原式=. 完形填空。      Breakfast is very important. It is one of   1   of the day. To keep healthy, everyone should   2   agood breakfast .   3   the right food is necessary for good health . We way have eggs, bread, milk, etc.(等等)  4   breakfast .      Many students go to school without breakfast   5   they get up late or their parents don't cook for them . It's   6   for their health.        7   breakfast children may not grow fast and may not study and play very well at school. They may   8  . And when they're ill, they will   9   a long time in recovering (恢复).       I think everyone should have some good   10   habits . (     )1. A. important                 meals (     )2. A. to have      (     )3. A. Eating      (     )4. A. in        (     )5. A. why        (     )6. A. good      (     )7. A. Without      (     )8. A. is ill    (     )9. A. spend        (     )10. A. health      B. the most important     mealsB. having               B. To eating           B. with               B. because             B. nothing             B. With                 B. ill               B. take               B. healthy              C. the most important    mealC. have                 C. Eats               C. on                 C. so                 C. bad                 C. Under                 C. are ill               C. cost               C. healthily              D. most important      mealsD. has                 D. Eat                 D. for                 D. but                 D. better              D. No have             D. be ill              D. make                D. bad