【单选题】100ml溶液中含有8mg Ca2+,则溶液中Ca2+的浓度是( )。
【单选题】浮在水面的船舶所受浮力的作用点称为浮心.关于浮心与船的质心,下面说法正确的是
D.
一旦船舶发生微小的侧倾,重力和浮力将构成力偶,其力矩使船倾覆.
【简答题】通过阅读“千熬万制的麻糖”的案例,谈谈其商业文化价值。
【单选题】What kind of machine can generate negative ions indoors?
【简答题】A ( )is a combination of positive and negative ions in the proper ratio to give a balanced charge and the name of the compound follows from names of the ions.
【判断题】Negative ions are smaller than the corresponding atom.