instruction:
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.
question:
Fact: a pulley is used for lifting objects.
answer:
how to make a pulley.


question:
Fact: Fertilization occurs when sperm swim to an egg inside an archegonium.
answer:
Fertilization fuse.


question:
Fact: coal is used for generating heat by burning.
answer:

burning coal pollution.