填+、-、×、÷，使算式成立。
14○2=7 18○8=10
3○9=27 19○7=12
÷；- ；×；-
We all agree with you, so we hope you _____ change your idea. [ ]
A. had better not to
B. would better not
C. would better not to
D. had better not
化学知识在日常生活中有很多应用，下列有关叙述正确的是
A．用食盐易清洗热水瓶中的水垢
B．用米汤检验含碘盐中的碘酸钾
C．漂白粉在空气中容易变质的原因是Ca(ClO)2见光易分解
D．利用丁达尔效应区别蛋白质溶液和食盐水
