How to allocate tasks to users on Roles in asp.net membership

Hi,
   My application have 2 Roles. Admin and Student. I created some tasks for these 2 roles by using LoginView ( Edit RoleGroup). Once  user login, can see there allocated tasks. 
   But I want to allocate some admin tasks to some student(s) not for all. How can I do it?
 
Thanks.
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