Which sentence is wrong because it's not parallel?
big wave surfing is supposedly both a tremendous thrill and an extraordinary danger.
big wave surfing is supposed to offer both tremendous thrills and extraordinary dangers.
big wave surfing is supposed to be both tremendously thrilling and extraordinarily dangerous.
big wave surfing is supposed to be both tremendously thrilling and an extraordinary danger.

The sentence 'Big wave surfing is supposed to be both tremendously thrilling and an extraordinary danger.' is wrong because the tense and form of the first modifier "tremendously thrilling" is different from "extraordinary danger" and thus the sentence is not parallel because they do not follow the same form. 

Uh

He said he had no intention to be involved with any other suspects and that the incident occurred at a news conference 9in in the parking area and was also expected for an hour later and a few days before his arrest and he had a 7child and the two had been killed and two were injured in a c car 33crash incident in a c square on the scene in which the driver of the car parked on a bus at a bus stop in a coma and was also a suspect on a car crash near san jose on the interstate north on a highway from san diego county in new orleans where a woman is being charged in connection with the murder in her home state in a coma