Answer:
50% slipper footed, 50% non-slipper footed
Acid rain<span> is caused by a </span>chemical<span> reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other </span>chemicals<span> to form more </span>acidic<span> pollutants, known as </span>acid rain<span>.</span>
The parachute was invented 4,000 yrs ago! :)
