Answer:
on ,by, in ,an,of,on, at,at,of
Humanity's early fire-starting tools may have been dangerous because in the text is says,<span> "It could be lighted only by hard rubbing, and it sputtered and threw fire in all directions." This is dangerous because it would spew fire in all directions and if you think about it, the fire would hit something and then that thing would catch on fire. Lets say you were using the match inside your house. When you strike the match, a spark flies onto the wood floor and your house goes up in flames and you are stuck inside the house with no exit or escape. This may or may not happen, but because of the fire not being contained, there was a chance that you would be harmed.</span>
Explanation:
Everyone enjoyed the celebration
where everyone is indefinite pronoun.
Answer:
he doesn't study hard is the negative form.
