No children           to watch this kind of movie because it's too scary.[ ]

A.  should alow                      

B.  shouldn't be allowed            

C. should be allowed                      

D. don't allow

指出异养微生物对下列氮源物质利用的先后次序：简单蛋白质，铵盐，N2，蛋白胨，硝酸盐。