The answer to your question should be true.
Here, you would need to add the preposition "in."
The sentence should read: My elder sister is really interested in the problems of the environment.
Other prepositions would not make sense and could confuse the reader as to the intended meaning.
Dove is the correct way to say it.
Answer: Rose and her mother were shopping for a birthday gift for Rose's older brother. "How about this? My brother would love it!" Rose exclaimed, showing her mother a pink and purple toy horse with flowing mane and tail. Beverly's belief that her teenage brother would enjoy a toy that she herself would enjoy is an example of <u>egocentrism</u>.
