The question in the title is strongly shortened. In full-length it goes like this:
Do people who speak fluently two languages (which they have learned as a child) that are quite different from each other (e.g. German and Arabic) learn a third language as a foreign language which is quite different from the other two (e.g. Chinese) more easily than those who speak fluently only one language learn a second language as a foreign language?
- Is there evidence by studies?
- To which extent?
- Depending on age?
References to specific studies are welcome!
The question aims at linguistic universals (à la Chomsky), not at learning techniques.