Explorer of the Extreme Deep？？ Oceans cover more thantwo-thirds of our planet.Yet,just a s

Explorer of the Extreme Deep

？？ Oceans cover more thantwo-thirds of our planet.Yet,just a small fraction of the underwater world hasbeen explored. Now, Scientists at the Woods olel Oceanographic Institution(WHOI) in Massachusettsare building an underwater vehicle hat will carry explorers as deep as 6, 500meters (21,320 feet). The new machine, known as a manned submersible orhuman-operated vehicle (HOV) , will replace another one named Alvin which bas an amazing record ofdiscovery, playing a key role in various important and famous underseaexpeditions. Alvinhas been operating for 40 years but can go down only 4,500 meters (14,784feet). It's about time for an upgrade,WHOI researchers say.

？？ Alvin was launched in 1964. Since then, Alvin has worked between 200 and 250 days a year, says Daniel Fornari,a marinegeologist and director of the Deep Ocean Exploration Institute at WHOI. Duringits lifetime, Alvinhas carried some 12,000 people on atotal of more than 3,000 dives. A newer, better versions of Alvin is bound to reveal even more surprisesabout a world that is still full of mysteries, Fornari says. It might also makethe job of exploration a little easier. "We take so much for granted onland, " Fomari says. "We can walk around and see with our eyes howbig things are. We can see colors, special arrangements. "

？？ Size-wise, the new HOV will？？be similar to Alvin.It'II be about 37 feet long. The setting area inside will be a small sphere,about 8 feet wide,like Alvin,it'II carry a pilot and two passengers. It will bejust as maneuverable. In most other ways,it will give passengers moreopportunities to enjoy the view,for one thing. Alvin has only three windows,the new vehiclewill have five,with more overlap so that the passengers and the pilot can seethe same thing.

Alvin can go up and down at a rate of 30meters every second,and its maximum speed is 2 knots (about 2. 3 miles perhour) ,while the new vehicle will be able to ascend and descend at 44 metersper second It'II reach speeds of 3 knots,or 3. 5 miles per hour.

What is Alvin？？？？？？？

A.research institute

B.A transporting vehicle

C.A submersible

D.A scientist