Language points
4. On average, there are 800 tornadoes in the US each year, causing about 80 deaths and 1,500 injuries. Causing…是形式作结果状语, 表示两个动作之间具有必然的因果关系,通常放在句末. 80多个国家都踢足球,使得它成为世界上最流行的运动. Football is played in more than 80countries, making it the most popular game in the world.