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:
"John hopes the sleeping bag will keep the den dark and the bear calm a bit longer."
Explanation:
John wants the bear to calm down, and he wants to keep the darkness within his refugee by covering the entrance with the sleeping bag, He is hiding from the bear because he wants to avoid being attacked by it.
Answer:
The Emancipation Proclamation
Explanation:
1863 during Abraham Lincoln's president time