A. EXTINCTION B. ENDANGERED C. BUSINESS D. INTENTIONREAD THE FOLLOWING...

Câu 70: A. extinction B. endangered C. business D. intentionRead the following passage and blacken the letter A, B, C, or D on your answer sheet toindicate the correct answer to the following questions.Lake Baikal, the world’s largest lake, is located in southern Siberia, in Russia. It measures395 miles of coastline. The lake’s rocky basin consists of three depressions, which hold a totalvolume of 14,656 cubic miles of water, 20 percent of the freshwater in the world. The lake isalso very deep, with its deepest point at over 1 mile and an average depth of 2,066 feet.Furthermore, scientists have determined that Lake Baikal is the oldest lake in the world. Fromsediment obtained by drilling deep down below the lake, researchers estimate it to be at least 25million years old.To scientists, Lake Baikal is of particular interest because of its unique and isolatedecosystem. More than 1,000 species of plants and animals found at Lake Baikal exist nowhereelse on earth and some can be dated to prehistoric times. Among its unique fauna is the Baikalfreshwater seal. This creature, which local people call nerpa, is the only mammal which inhabitsthe lake. Researchers speculate that these seals, which have been breeding at Lake Baikal for 22million years, are the descendents of ocean -dwelling seals which migrated inland in search offood, when the lake was still connected to the sea. Another creature that is unique to this SiberianLake is the omu, a fish, which is caught by local fisherman and is considered a great delicacy.For centuries, the water in Lake Baikal was so clear that it was possible to see down todepths of 40 to 60 feet. First, the lake contained certain small zooplankton and small crustaceansthat consumed waterweeds, bacteria, and other material that would otherwise cloud the water.Furthermore, the water in the lake consisted of rainwater and melted snow that flowed downfrom a mountain range in about 300 streams and through uninhabited forest. Finally, most of thewatershed has a rocky surface, so the water flowing into the lake did not accumulate mud ororganic matter and had little mineral or chemical content.