In this task, you're given a pair of sentences, sentence 1 and sentence 2, that agree with each other. Your job is to alter sentence 2 so that the pair contradict each other. Generated sentences must be short, with less than 15 words. New information can be introduced. Avoid using pronouns to confuse the subject of the sentence.

Sentence 1: A person wearing a hat and baggy pants is skateboarding on cement. Sentence 2: A human rides a skateboard.
An old man falls off a skateboard.

Sentence 1: Two people wearing hoodies huddle on a doorstep in the rain. Sentence 2: Two people huddle in the rain outside.
Three people stand outside the doorstep in the snow.

Sentence 1: A man riding an unsual bike in a bike race. Sentence 2: A man is riding a strange bike during a race.

A man is riding a horse in London.