There are many causes for global warming in the world today. The ______ (1.A. absorb; B.allow; C.continues; D. leading; E.ongoing; F.quantities; G.solutions; H.thinned) cause of global warming is the ______ (2. A.absorb; B.allow; C.continues; D.leading; E.ongoing; F.quantities; G.solutions; H. thinned) burning of fossil fuels, which releases carbondioxide into the atmosphere. Carbon dioxide, along with the other greenhouse gases of methane, nitrous oxide, and chlorofluorocarbons, is the cause of the greenhouse effect. This effect is dangerously increasing as the gases are being released in greater ______ (3. A.absorb; B.allow; C.continues; D.leading; E.ongoing; F.quantities; G.solutions; H.thinned) . These gases not only build up to keep heat in the atmosphere, but they also thin the ozone layer. Some areas have been so ______ (4. A.absorb; B.allow; C.continues;D.leading; E.ongoing; F.quantities; G.solutions; H.thinned) by the gases that there are holes present in the ozone. These dangerous holes ______ (5. A.absorb; B.allow; C.continues; D.leading; E.ongoing; F.quantities; G.solutions; H.thinned) harmful rays from the sun to reach the earth. Those rays are the main cause of skin cancer. As the earth ______ (6. A.absorb; B.allow; C.continues; D.leading; E.ongoing; F.quantities; G.solutions; H.thinned) to increase its pollution level each year, the number of skin cancer patients increases.