¿How i do for unskip an activity by powershell script?

Question

Hi.
Im looking a way for unskip an activity from a service request using a powershell script.
I've obtained for example the review activities.....
$activities
= Get-SCSMRelatedObject
-SMObject
$srObj
–Relationship
$wiContainsActivity
$reviewAct
= $activities
| Where {$_.ID -match
'RA'}
Now i need to unskip an specific activity filtering by name for example .
Regards.

Answer 1

Thanks Thomas.
I've tested the solutions but none work. 
My problem is that im looking a way for dont create many service request templates (only
one service request template but many activities templates).  I thought about create a classification enum list in a service request template with authoring tool (VALUE EXAMPLES: email, printer, vm creation) and find the way to create a workflow that
add automatically the activities when i change the list value.
A member of the community told me this:
"Hi,
You can create a single SR template and add additional activities and skip them as by default. Then create a workflow (or use SCORCH) to unskip the required activities. It much easier than adding new activities 'on-fly'."
And i've created an authoring tool WF that run when a service request is created and execute
the next pwshell script for unskip the review activities skipped in the service request that by default are skipped in the template but is not running. Can you help me? what's wrong?
set-executionpolicy -executionPolicy ByPass
$a = (get-module|%{$_.name}) -join " "
if(!$a.Contains("SMLets")){Import-Module SMLets -ErrorVariable err -Force}
$srClass = Get-SCSMClass System.WorkItem.ServiceRequest$
$srObj = Get-SCSMObject -Class $srClass | Where {$_.ID -eq $srID}
$wiContainsActivity = Get-SCSMRelationshipClass System.WorkItemContainsActivity
$activities = Get-SCSMRelatedObject -SMObject $srObj –Relationship $wiContainsActivity
$reviewAct = $activities | Where {$_.ID -match 'AR'}
$ACStatusSkipped = Get-SCSMEnumeration ActivityStatusEnum.Skipped
$ACStatusReRun = Get-SCSMEnumeration ActivityStatusEnum.Rerun$
If ($reviewAct.Stauts -eq $ACStatusSkipped) { 
  set-SCSMObject $reviewAct -Property Status -Value $ACStatusRerun
}