Definition: In this task, you need to write a topic word from the given fact. The topic word must have at least one word overlap with the given fact. The topic word often involves adding a new word from a related concept. In your topic word, use at least one word from the given fact. Topic words with two or more words work best.

Positive Example 1 -
Input: Fact: pesticides cause pollution.
Output: pollution harms.

Positive Example 2 -
Input: Fact: pesticides cause pollution.
Output: modern farming pesticide.

Negative Example 1 -
Input: Fact: pesticides cause pollution.
Output: computer harms.

Negative Example 2 -
Input: Fact: pesticides cause pollution.
Output: toopaste helps.

Now complete the following example -
Input: Fact: gases from burning coal and oil dissolving in water in the atmosphere causes acid rain.
Output: 


Output:
Acid is defined as.
acid rain environment.
acid rain kills plants.
acid rain ph.
acid rain polluted.
acid rain.
burning coal.
coal acid rain.
gases from burning coal.
gases vapor.