Dogs and other hairy mammals shake at just the right frequencies to get rid of water most quickly from their bodies-and directly on to any unlucky humans nearby．Mice do it．So do tigers and pandas．These animals really know how to shake．Frequency is the number of cycles-movements back and forth-per second．
Researchers at the Georgia Institute of Technology in Atlanta recently recorded videos of 40different animals，standing for 15different species．The scientists wanted to see how wet，hairy mammals shake off water after they get wet．The scientists say the animals shake at just the right frequencies to lose water drops as quickly as possible．"I think it's pretty amazing that they can do that，"David Hu，one of the scientists，said．
This study was led by Andrew Dickerson，a graduate student in Hu's lab．His team calls this get-dry shake"nature's analogy（类似） to the spin cycle of a washing machine"．Both the washing machine and shaking animals can get rid of water quickly-but animals are much faster than washing machines．For animals，this process helps them control heat in their bodies．
"If a dog couldn't dry itself，it would have to use 25percent of its daily calories to heat its body to get rid of the water，"Hu said．"Every time they got wet they would get hypothermia and die．"
The bigger the animal，the slower it shakes，according to Dickerson and his team．A mouse moves its body back and forth 27times per second，but a bear shakes only four times per second．
Animals'skin also helps them get rid of water．The scientists are continuing to look at how animals interact with water in the natural world．In particular，the scientists want to know how water interacts with hair-which means studying animals that have got used to life in the water，like beavers and otters．

(1) Which of the following animals is not likely to be studied in the experiments？ ______

A. A panda．

B. A tiger．

C. A cat．

D. A snake．

(2) What can we learn from the passage？ ______

A. Professor David Hu led the study．

B. A dog shakes off water at a higher speed than a washing machine．

C. Animals shake off water to keep themselves cool．

D. A dog shakes off water faster than a mouse．

(3) How did David Hu feel about the video？ ______

A. Surprised．

B. Encouraged．

C. Excited．

D. Amused．

(4) Which of the following does hypothermia probably refer to？ ______

A. a disease caused by hunger

B. a disease caused by getting too hot．

C. a disease caused by getting too cold．

D. a disease caused by shaking too fast．