TASK DEFINITION: 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.
PROBLEM: Fact 1: using renewable resources to generate power reduces greenhouse gases. 
Fact 2: Nuclear power generation plants emit no greenhouse gases.

SOLUTION: Nuclear power plants reduce greenhouse gases.

PROBLEM: Fact 1: Protozoa can be classified on the basis of how they move. 
Fact 2: For ease of identification, cotton seedlings are classified into the following three categories.

SOLUTION: Protozoa can be identified by how they move.

PROBLEM: Fact 1: if gas is heated then that gas will expand. 
Fact 2: Water vapor is a gas in the air.

SOLUTION:
if water vapor is heated then it expands.