Appositive

I'm sorry I hand in this late.. I really don't know how to expain that even in Chinese^^But I searched some information about that online, they are useful.
A noun or some other forms modify another noun then restrict or illuminate it, the noun or the form can considered to be an appositive. Sometimes it can stress the tone of the sentence. It is hard to find the difference between appositive clause and attibutive clause in grammar. Such as the word "that", it has no exact meaning in appositive clause, it is used for linking and leading the clause. But in attibutive clause, "that" is an element of the clause and it can be omitted when it is the object of the clause. Now I can use some example to explain the appositive clauses.
1.Yesterday I met Tom, a friend of mine.
Here, "a friend of mine" is modifying "Tom" so that "a friend of mine" is the appositive of "Tom".
2.How can a solution be found to the current disease of contemporary society, namely the international economic crisis?
This is a non-restrictive appositive clause. Sometimes we will add something in the sentence so that it is clearer to show the non-restrictive character in the sentence.
These are all my understanding of appositive clause or appositive. :)
I hope I explained them well. :P