Answer:
Difficult but beneficial
Some researchers
Strengthen memory
new possibilities
Explanation:
Based on inferences deduced from the passage, it could be deduced that being bilingual(ability to speak two languages) is good and advantageous, but also difficult, as the second language may need to be learnt, as it will likely differ from one's mother tongue. Being bilingual has being said by some researchers to help brain functionality and strengthen memory even though it hasn't been well established.
Howerver, it is well established that being bilingual aids development as it opens up networks of opportunities, relationships and experience.