In this task, you're given a pair of sentences, sentence 1 and sentence 2, that neither agree with nor contradict each other. Your job is to alter sentence 2 so that the pair clearly 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 man riding a green motorcycle jumping nine other green motorcycles. Sentence 2: A man crashed while jumping over obstacles on his motorcycle.
A man is performing tricks on his powerfile bike.

Sentence 1: Three women, one old, one young and one a child, walk down a street. Sentence 2: The women aren't alone on the street.
Women are walking down the street.

Sentence 1: A young boy, dressed in a karate gee and wearing a yellow belt, stands ready to defend himself inside a gym. Sentence 2: A yellow Belt Karate Student is fighting a White Belt Student.

the boy is a karate student