选择单词或词组，用其适当的形式填空，使句子意思正确、通顺。每词限用一次，其中两词多余。

certainly, build, prepare, rich, meaningless, turn on, turn down

【小题1】We should work for ________ but hope for the best.
【小题2】P.E. is ________ the kids’ favorite subject because they can relax for a while.
【小题3】They ________ a new school to improve the environment for students but asked for nothing.
【小题4】It is hard for us to ________ an ice cream but it is really not good for our health.
【小题5】You should make a full ________ for the exam, or you’ll lose it.