On November 7， Lewis Pugh completed a one-kilometer swim in the freezing waters of King Edward Cove， off South Georgia in Antarctica． He was wearing only his swimming glasses， cap and Speedos （速度计）．
Pugh is an advocate （提倡者） for our oceans and seas， working to protect these ecosystems （生态系统） with their large diversity of sea life． When asked why he doesn't wear a wetsuit， Lewis says， " I ask world leaders to do everything they can to protect our oceans． Sometimes the steps they need to take are difficult and unpopular． If I'm asking them to be courageous， I must also be． Swimming in a wetsuit would not send the right message．"
It took Pugh about 19 minutes to complete the one-kilometer swim in Antarctica where the water averaged about 1.6 degrees Celsius． He says that his body can only tolerate about 20 minutes in the freezing waters before it starts shutting down． As he swims， his body temperature steadily drops， which in turn causes his muscle control to drop， slowing him down． When he is done with his swim， his support team rushes him to a hot shower and it takes almost an hour for his body temperature to return to normal．
Doctors and Pugh warn that one must receive months of training to swim in such cold waters． Even expert swimmers who are unused to freezing water can drown within minutes because of the physical shock experienced by the body． Pugh says he trained for six months before this swim．
This is not the first time that Lewis has swum in dangerous conditions． In 2007， he swam one kilometer in the North Pole to draw attention to the melting Arctic ice due to the climate change． In 2015， he swam in the Bay of Whales in Antarctica's Ross Sea as part of his successful campaign to help set up a sea life reserve （保护中心） there．



Why did Lewis Pugh swim without a wetsuit？ ______

A. To swim faster．
B. To protect the ecosystems．
C. To win public attention．
D. To show his bravery．

What does the underlined word "it" in Paragraph 3 refer to ______ ？

A. His body temperature．
B. His muscle．
C. His body．
D. The water temperature．

According to the passage， if one is going to swim in freezing waters， he ______ ．

A. should be expert at swimming
B. should be ready to take on challenges
C. must be trained professionally
D. must be used to long-distance swimming

What may be the best title for the text？ ______

A. Tips for protecting oceans and seas
B. Lewis Pugh： swimming for a cause
C. Tips for extreme swimming
D. Lewis Pugh： achieving the impossible