Exercise 8:
A tornado is a violently rotating column of air that extends from a thunderstorm—although not always visible as a funnel cloud. Lightning and hail **are** common in thunderstorms that produce tornadoes. Tornadoes **cause** extensive damage and disrupt transportation, power, water, gas, communications, and other services in their neighbouring areas. Related thunderstorms can cause heavy rains, flash flooding, and hail. About 1,200 tornadoes hit the United States every year, and every state is at risk. Most tornadoes **occur** east of the Rocky Mountains with concentrations in the central and southern plains. They **occur** most often in the spring and can occur at all hours of the day and night, but are most likely to occur between 3 pm and 9 pm.
Exercise 9: A. Hurricanes and tornadoes.