Answer:
A drought would cause a lot of the plants in that ecosystem to die which makes herbivores struggle to find food.
Lincoln helped America through the civil war, he signed the Emancipation Proclamation to end slavery, he tried to keep the country together. Keeping America together is so important because if sectionalism continues the U.S. may split apart. Our country would not be united, but separated.
These is the demonstrative pronoun. These,this are pronouns demonstrative.