Câu hỏi:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 26 to 30.

 Tornadoes are giant rotating columns of air. They form in thunderstorms when there is a great difference in the temperature and humidity of the lower and upper atmosphere. They can be very dangerous and very destructive. There are different varieties of tornadoes. They can be very big or small. Some tornadoes are only a few feet across and others can travel across an entire state. Tornadoes· stretch from the ground high into the sky. Usually, people rate them from F0 to F5, F5 being the most dangerous with wind speeds of around 261-318 miles per hour. They are a very violent force of nature and can lay whole towns completely flat. Tornadoes can happen all over the world but a lot of them happen in the central United States in a region called Tornado Alley. Tornado Alley is made up of the low, flat states of the central United States between the Rocky Mountains and the Appalachian Mountains. Even though Tornado Alley is the most common place for tornadoes, the deadliest recorded tornado was in Bangladesh in 1989 and killed around 1,300 people. Recently, massive tornadoes destroyed large parts of Alabama in the United States, a state that does not usually have tornadoes. 

Which of the following is NOT true about tornadoes?