When harold went racing down the hill on his sled. he hit a large bump and flew into the air, and landed safely on the ground.

how is the sentence fragment best corrected?

martians or other types of aliens represent a unique fear as opposed to zombies. vampires and other types of monsters.   in most sci-fi stories, aliens come from other worlds and have different or more advanced technology.   abductions and experimentation on human bodies that involve these technologies, or the use of these technologies against human beings and the use of unknown "powers", are a type of fear that's different from that of other types of monsters.  

all of the statements cuz