instruction:
Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
question:
Fact 1: landfills have a negative impact on the environment. 
Fact 2: An ecosystem is an environment and all the members of that environment.
answer:
Landfills have a negative impact on the ecosystems.


question:
Fact 1: Insects can spread disease and destroy crops. 
Fact 2: Major crops are corn, peanuts, soybeans and horticultural crops.
answer:
Insects can spread disease to things such as corn, peanuts and soybeans.


question:
Fact 1: a airplane is used for moving people across bodies of water. 
Fact 2: Jet airplanes burn fuel throughout the flight to overcome air resistance.
answer:

a jet is used for moving a large amount of people across bodies of water.