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: Roundworms reproduce sexually. 
Fact 2: Nematodes are simple roundworms.
answer:
nematodes reproduce sexually.


question:
Fact 1: Corals form large colonies in shallow tropical water. 
Fact 2: Corals are tiny flower-like animals that live in colonies.
answer:
Flower-like animals live in shallow tropical water.


question:
Fact 1: damming a river can cause a lake to form. 
Fact 2: You can also water ski on Lake Mohave north of Davis Dam.
answer:

damming a river opens new areas for water skiing.