A:①②
B:②③
C:②④
D:①④
1,2,3-三苯基环丙烷的三个苯基可以分布在环丙烷环平面的上下,从而形成异构体,如下图所示。据此可知1,2,3,4,5五氯环戊烷(假定其五个碳原子在同一平面上)的异构体数目是( )
7×____>55
____×5>44
School violence ______ much attention of the whole society and people are calling on the government to make laws against it as early as possible.
下列现象中不属于大气压强现象的是( )