She is a bit immature to assume so many responsibilities.
Advanced English Dictionary
+adjective 1 behaving in a way that is not sensible and is typical of people who are much younger: immature behaviour + He's very immature for his age. 2 not fully developed or grown: immature plants Antonym: MATURE immaturity noun [U]
Collocation Dictionary adj
very | rather, relatively | emotionally, physically, politically, sexually
Random quote: Ability is what you're capable of doing. Motivation determines what you do.Attitude determines how well you do it.: Lou Holtz