题目

计算： （1） ； （2） . 答案：解：原式= −13−223+316−616 =−3−3 =-6 解：原式= −8×32×32×19 =−2The problem of waste is becoming more and more common , so it must be controlled . Every day , a number of ___21___ goes uneaten (没吃) and ends up in the trash , while many people in developing countries cannot even ___22___ to have one meal every day . The next time you ___23___ to a delicious dinner , ask yourself , “How much food will I ___24___ eat ? ” If you think about only taking as much as you can ___25___ , it will help you cut down ___26____waste . The problem of waste ___27___all over the world . People often consume(消费) ___28___than they really need . This often results in waste and it can be a big ___29___. However , there are many things ___30___we can do to help cut down on trash and waste . The most important thing to remember is to be friendly to the ____31___ . Only take as much as you can eat , don’t buy things you neither want ___32___ need , and leave litter in its proper place . ____33___every person could cut down on waste in daily lives , even just____34___ , the whole result would be great . We know that many restaurants have joined the “clear your plate” campaign against ___35___food. We students should do the same in our daily life especially when having dinner with our friends and relatives. (    )21.A. fruit              B. vegetable        C. meat               D. food (    )22.A. buy              B. pay            C. spend               D. afford (    )23.A. sit down           B. put down        C. come down         D. walk down (    )24.A. can               B. could           C. be able to           D. am able to   (    )25.A. cook              B. make           C. buy                D. eat   (    )26.A. of                B. on              C. about              D. in (    )27.A. sees              B. has             C. happens             D. takes place (    )28.A. many             B. much           C. more               D. most (    )29.A. problem           B. question         C. difficulty            D. puzzle (    )30.A. what              B. that            C. whether             D. so that   (    )31.A. people             B. food           C. environment         D. life (    )32.A. or                B. nor             C. and                D. either (    )33.A. Though            B. Until           C. If                  D. Unless (    )34.A. little               B. a little          C. few              D. a few (    )35. A. buying            B. selling          C. saving            D. wasting