Answer:
Deleting everything except the first sentences of each numbered step.
Explanation:
The first sentences actually tell you what to do while the rest just explains why they're telling you to do it. If you read that article, all you would want to know are the steps to prevent crying while cutting onions, not necessarily the science behind those reasons.
Well, a magnet could DEFINITELY change if it gets exposed to heat, because you could melt the metal and change its shape.
If you hit it hard though, it wouldn't make much of a difference because the magnet is metal, so you'll probably just chip it or leave a dent.
Hope this helps ;)