Alaskan black bears hibernate for up to seven months a year, during which time they do not eat or drink, before waking up in virtually the same physical state they fell asleep in．
Now experts hope to develop methods of putting humans into a similar state which could help astronauts survive long missions and lead to new ways of treating severely ill patients．
While many studies have examined hibernation in mice and hedgehogs, little research has been done into the same condition in larger mammals such as bears．
But new research conducted at the Institute of Arctic Biology at the University of Alaska monitored the animals' body temperature, heart rate and muscle movements while they slept.
The research results showed that during a five-month hibernation the bears’ body temeratures varied between 30℃ and 36℃ in cycles that lasted between two and seven days—a pattern that was previously unknown in hibernating animals.
The research project leader said, "If our research could help by showing how to reduce metabolic(新陈代谢的) rates and oxygen demands in human tissues, one could possibly save severely ill patients. We simply need to know how to turn things on and off to take advantage of the different levels of hibernation."
Craig Heller, of Stanford University, who contributed to the study, added: "There has always been a thought that, if there is ever long-distance space travel, it would be good to be able to put people into a state of lower metabolism or a state of hibernation. That's almost science fiction but you can see the logical basis."
We know from the text that            .

A．during winter Alaskan black bears sleep for more than half a year

B．researchers have examined hibernation in humans

C．experts have got no results from their research

D．Craig Heller is a leader from the Institute of Arctic Biology

The best topic of the text should be                ．
． 

A．The Latest Research Results

B．New Methods of Putting Humans into Hibernation

C．Alaskan Black Bears Hibernate

D．Astronauts Could Hibernate Like Bears

According to the text, we can infer that         .

A．many studies have examined hibernation in mice and bears as well

B．humans' body temperatures vary between 30℃ and 36℃ while they sleep

C．research into hibernation in animals may help deadly patients stay longer

D．scientists have already take advantage of the different levels of hibernation in space missions