题目内容：

    Sea turtles are one of several species that have temperature-dependent sex determination. The number of female babies increases when nests are made in warmer sands.

A recent study by the National Oceanic and Atmospheric Administration, California State University and Worldwide Fund for Nature Australia examined two genetically distinct populations of green sea turtles living in the Great Barrier Reef. The study found that a group of about 200,000 turtles living in the northern part of the reef was almost entirely female.

While the southern population was 65 to 69 percent female, females in the northern group accounted for 99.1 percent of young turtles and 86.8 percent of adults.

After combining their results with temperature data, the scientists in charge of the study found that the northern green turtles have been producing mainly females for more than two decades and that the complete feminization(雌性化) of this population is possible in the near future.

The temperature at which the turtles will produce male or female babies can be passed on to the turtles' children. Most sea turtle populations are now producing offspring above the most suitable temperature, making it clear that climate change causes a serious threat to the survival of these populations.

The chief executive Of World Wildlife Fund Australia, Dermot O'Gorman, said this is another sign of the impact of climate change, following recent research that shows that coral bleaching (珊瑚白化) events are occurring far more frequently than in the past.

“We've had two years where we've had mass bleaching events on the Great Barrier Reef,” he told Guardian Australia. “That's a very visible sign of the impact of climate change. But this is a quiet change. We can't see the impact it's having on a turtle population until a study like this shows some long-term trends.”

The lead author of the paper, Dr Michael Jensen, said the findings represent a major environmental conservation issue.

O'Gorman said more urgent action on climate change is clearly needed, adding that some conservationists have already taken practical measures, such as using shade cloth on turtle nesting beaches to lower the sand temperature, and reducing bycatch(误捕) in the fishing industry.

"Shade cloth can be used in certain places, but there's a limit to the scale you can do that, " he said. "Now every large male who can reproduce is going to be even more important.

1.According to the research on Great Barrier Reef's green sea turtles, __________.

A.about 65 to 69 percent of northern turtles are female

B.86.8 percent of southern turtles have grown up to adults

C.the feminization of green sea turtles could become worse

D.adult green Sea turtles can change their sex in warmer places

2.Why did O'Gorman mention coral bleaching?

A.To suggest that climate change poses more risks to coral than turtles.

B.To compare the living environments of turtles and coral.

C.To urge people to take practical measures to fight climate change.

D.To stress this discovery about green sea turtles is very valuable.

3.Conservationists are taking action to __________.

A.keep the sea turtles' nests cool

B.stop the illegal fishing of green sea turtles

C.expand the size of the green sea turtles' nesting places

D.build special nests for turtles to produce offspring

4.Which would be the best title for the article?

A.How climate change affects ocean creatures

B.Invisible change caused by global warming exposed

C.Necessity of protecting green sea turtles and their habitat

D.Global green sea turtle populations in greater danger