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.

Example Input: Fact 1: Earthworm burrows help aerate soil, which is also good for plants. 
Fact 2: Good drainage is essential for growing plants in containers.
Example Output: Earthworm burrows help aerate soil, which is essential for growing plants.

Example Input: Fact 1: skin is used for breathing air by frogs. 
Fact 2: Air contains oxygen.
Example Output: skin is used for breathing oxygen by frogs.

Example Input: Fact 1: Placental mammals are therian mammals in which a placenta develops during pregnancy. 
Fact 2: Placental mammals give birth to live young, and house the embryo until it is complete.
Example Output:
Mammals that are therians house the embryo until it is complete during pregnancy.