Hi, Maged Hosny,
[as well as] is a preposition or conjunction?
As a linker of addition, "as well as" is halfway between both parts of speech.
Quirk and Greenbaum define it as a quasi-coordinator. On page 275 of their A University Grammar of English, they explain that quasi-coordinators sometimes resemble coordinating conjunctions and give this example:
- He publishes as well as prints his own books.
But they add that they can also have a prepositional or subordinating role, as in:
- As well as printing the books, he publishes them.