题目内容：

We all think plants were expected to get larger with increased carbon dioxide in the atmosphere, but changes in temperature, humidity(湿度)and nutrient availability seem to have trumped the benefits of increased carbon dioxide” said researchers from the National University of Singapore.

45 percent of the species studied now reach smaller adult sizes than they did in the past. The researchers pointed out that warmer temperatures and changing habitats, caused by climate change, are possible reasons for shrinking creatures.

“ We do not yet know the mechanisms(机制)involved, or why some organism are getting smaller while others are unaffected,” the researchers said. “Until we understand more, we could be risking negative consequences that we can’t yet quantify. ’’

The change is big in cold-blooded animals. Only two decades of warmer temperatures are enough to make retiles (爬行动物)smaller. An increase of only 1 degree centigrade caused nearly a 10 percent increase in metabolism(新陈代谢). Greater use of energy resulted in tiny tortoises and little lizards. Fish are smaller now too. Though overfishing has played a part in reducing numbers, experiments show that warmer temperatures also stop fish growing.

Warm-blooded animals aren’t immune(免除)from the size change caused by climate change. Many birds are now smaller. Soay sheep are thinner. Red deer are weaken And polar bears are smaller, compared with historical records.

This is not the first time this has happened in Earth’s history. 55 million years ago, a warming event similar to the current climate change caused bees, spiders and ants to shrink by 50 to 75 percent over several thousand years. That event happened over a longer time than the current climate change.

The speed of modem climate change could mean organisms may not respond or adapt quickly enough, especially those with long generation times climate change will be shown in the future.

1.What does the text mainly talk about_______

A. Why some species become smaller.

B. How climate changes in Earth’s history?

C. Climate change has many negative effects.

D. Species are becoming smaller as climate gets warmer.

2.The underlined word “trumped” m the first paragraph probably mean_________.

A. strengthened    B. gained

C. beaten    D. equaled

3.Researchers from the National University of Singapore believe that________

A. they have found the exact causes for creatures getting smaller.

B. all the animals on the earth have become smaller.

C. climate change has more negative effects on warm-blooded animals.

D. increase in energy use can lead to creatures getting smaller.

4.What does the author feel about the climate change?

A. Disappointed    B. Optimistic

C. Worried    D. Shameful