come back回来

come down降下;减低

come in进来;到达

come out出来;出版

come up上来;被提出讨论;发芽

come up with追上;赶上

come to 结果达到;苏醒

20. heat up 受热

21. up to 多达; 比得上

22. in the years ahead 今后一些年里

23. carry out 执行

24. decrease by 下降了......

decrease (from ...) to （从......）下降到

25. greenhouse effect 温室效应 '

II. Sentences

1. That probably doesn't sound very much to you or to me but it is a rapid increase compared to most natural changes.

这对你我来说很可能是无所谓的，但是跟多数自然变化相比较而言，这却是一种快速的增长。

2. There is no doubt that the earth is becoming warmer but there is fierce debate over whether it is human activity that has caused this global warming or whether it is just a natural phenomenon.

毋庸质疑的是地球正在变暖,但关于它变暖的原因是由于人类活动所致还是一种自然现象还存在激烈的争论。

3. Without the "greenhouse effect", the earth would be about thirty-three degrees Celsius cooler than it is.

如果没有这种 "温室效应"，地球的温度将比现在的温度还要低33摄氏度左右。

4. Some people think future global warming would cause the sea level to rise by several meters; others predict severe storms, droughts, famines, the spread of diseases, and the destruction of species.

有人认为全球变暖会导致海平面上升好几米;也有人预言会出现严重的风暴、干旱、饥荒、