听短文，填入所缺单词。

     People in    1    like Christmas very much. They    2    it with their    3   . It usually comes in    4   . On

that day, children are very happy,    5    they can get lots of presents from their    6   . Usually, there is a

Christmas tree in their house. People sing and    7   . They all look very happy. At    8    , they have a nice

   9   with a lot of delicious (美味的)   10    .

α粒子散射实验结果表明（   ）

A．原子中绝大部分是空的

B．原子中全部正电荷都集中在原子核上

C．原子内有中子

D．原子的质量几乎全部集中在原子核上