题目内容：
Scientists say that something very serious is happening to the earth. It will begin to get 56 in the following years. There will be major changes in 57 in the new century.Coastal waters will have a 58 temperature. This will have a 59 effect on agriculture. In northern areas, the 60 season will be ten days longer by the year 2010. However, in warmer areas, it will be too dry. The 61 of water could 62 by eighty percent. This would 63 a large decrease in agriculture production.
World temperature could 64 two degrees centigrade by the year 2040. How-ever, the increase could be three times as great in the Arctic and Antarctic areas. This could cause the 65 sheets to melt and raise the 66 of the oceans 67 one to two meters. Many coastal cities would be 68 water.
Why is this happening? There is too 69 carbon dioxide in the air. 70 oil, gas and coal burn, they create large amounts of carbon dioxide. This carbon dioxide lets 71 enter the earth's atmosphere and 72 the earth. However, it doesn't let as much heat 73 the atmosphere and enter space. It's like a blanket. The heat
74 the sun can pass through the blanket to warm the earth. The heat 75 there and can't escape through the blanket again.
Scientists call this the green-house effect.根据以上内容，回答题。
A．warmer
B．colder
C．better
D．worse
参考答案：
答案解析：