题目

The Earth has warmed by about half a degree（0．50℃）over the last 100 years．It could be getting warmer on its own，but many scientists think that people are making the Earth warmer by making a greenhouse effect（温室效应）．The greenhouse effect is important． Without it，the Earth would not be warm enough for us to live on．But just a little warmer than it is now could cause（引起）problems for humans，plants and animals． Many of the things we do every day can change the Earth’s temperature by sending greenhouse gases（废气） into the air．We send greenhouse g淮河多水灾的原因是①支流多 ②每年南北支流同时进入汛期③流域内落差小 ④气候异常⑤暴雨频繁 ⑥季风活动的年际变化大⑦河道弯曲狭窄 ⑧湖泊淤积A．②③④⑥⑦B．①③⑤⑦⑧C．①③④⑤⑥D．②③④⑦⑧