In "My Last Duchess" by Robert Browning, the situation which brings the duke and the agent together is the duke's intention to remarry.
His wife died (or was killed, we will never know for sure), and he lost a lot of money, which is why he needs to marry into a rich family so as to regain what he lost. This is the reason why he met with the agent, so as to marry his cousin or something.
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.
Answer:
metaphor.......................
Answer:
I asked my sister for a cookie but she didn't give me one.
