finally i resolved the issue my self. for guidance please refer it.
;with cte as (
select task_id, short_name, ROW_NUMBER() over(partition by task_id order by a.actv_code_id) as rid
from ACTVCODE a
inner join [TASKACTV] b on a.actv_code_id = b.actv_code_id
select a.task_id, a.short_name, b.short_name as short_name1
from cte a
inner join cte b on a.task_id = b.task_id and a.rid = b.rid-1