Question

look at these details from a paragraph about the same topic: before a tornado, the sky may turn very dark and sometimes green. when a tornado is near, you may hear a loud roaring sound that lasts a long time. there can be hail or very heavy rain before a tornado strikes. choose the main, or central, idea that ties all the details together. there are a few ways to stay safe during a tornado. there are some signs that show a tornado is coming. heavy rain and hail can be signs of a tornado.

Explanation:

The details list phenomena like dark - green sky, roaring sound, hail, and heavy rain before a tornado. These are all signs indicating a tornado is approaching.

Answer:

There are some signs that show a tornado is coming.