“Plants were expected to get larger with increased carbon dioxide in atmosphere, but changes in temperature, humidity(湿度) and nutrient availability（养分有效性） seem to 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(缩小的) creatures.
“We do not yet know the mechanisms（原理） 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 was big in coldblooded animals. Only two decades of warmer temperatures were enough to make reptiles（爬行动物） smaller. An increase of 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 growth. There is a recent report on warmer temperatures' negative effects on plankton（浮游生物）, the base of the marine（海洋的） ecosystem.
Warmblooded animals weren't immune（免于） from the size change caused by climate change. Many birds are now smaller. Mammals have been miniaturized too. Soay sheep are thinner. Red deer are weaker. 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 long time than the current climate change.
The speed of modern climate change could mean organisms may not respond or adapt quickly enough, especially those with long generation times. So, it is likely that more negative influences of climate change will be shown in future.
Which of the following would be the best title for the passage? ________

A．Why do some species become smaller?

B．Species become smaller as climate warms

C．Climate change has many negative effects

D．How does temperature change in Earth's history?

The underlined word “trumped” in the first paragraph can be replaced by ________.

A．been neglected by	B．been less than
C．been weakened by	D．had strong influences than

Researchers from the National University of Singapore believe that ________.

A．too many studies on animals' size have been done

B．all the animals on the earth have become smaller

C．how climate change effects animals' size has not been found clearly

D．people can avoid the negative effects of climate change

What can we learn from the passage? ________

A．Ants, bees and spiders have been shrinking by 50% to 70% in the past decade.

B．Birds have suffered more from climate change than fish.

C．Climate change has even affected plankton negatively.

D．A warming event causing species to become smaller has never happened before.