Passage ThreeThe warming weather of the past hundred years may（）

A．begin
B．end
C．be another ice age
D．start

It is possible that the weather of the world may be changing. Some scientists imagine that this could even mean the beginning of another ice age. The effects of such a change in weather on human population of the world would be frightening.

Recent research suggests that the warming trend (倾向) of the past hundred years or so may be coming to an end. During the past ten years, scientists tell us that the temperature of the world has dropped a little. This would have effects on wind and rain in the weather picture.

Scientists believe clouds may be an important factor (因素) in changing the amount of heat on the earth. Another possibility is that man’s agriculture and industry ways may affect the natural weather.