Linq: Aggregate string array to string

Question:

I want to concatenate all strings of an array using Linq. How to?
How to use the aggregate method with enumerables of string?

Dot.Net: Asynch Method Call Sample

Question:

Do you have an example of a standard asynchronous method call with callback in CSharp ?
Any event driven asynchronous sample in dot.net ??

Dot.Net: Delegates and Actions

Question:

What is the difference between delegates and actions in csharp.

Dot.Net: Expose Custom Events

Question:

How do I expose custom events in a c# class?
How do I create custom event, event delegate, event arguments in dot.net?

Asp.Net: Generic Recursive FindControl Method

Question:

How to find a control in the whole page not just in the child collection?
How to find recursively a control in the child hierarchy of a control?

Csharp: Using predicates as arguments.

Question:

How to pass predicates as arguments to my methods?
I want to use predicates as test methods and pass them to a general test.