题干
There are ________ people having lunch at this restaurant every day.
A：hundred of
B：hundreds of
C：two hundred
D：two hundred of
答案(点此获取答案解析）
B
原子核在中子的轰击下发生一种可能的裂变反应，其裂变方程为
,则下列叙述正确的是( )