Circle the letter A, B, C or D that best fits  each of  the blank space in the following passage.  ​ One of the reasons why our environment is (1) ______ is that each household produces a lot of rubbish every day. In order to reduce the pollution, we need to increase the volume of rubbish that is recycled (2) ______ we cannot carry on burying and burning rubbish forever. This means that we should (3) ______ the amount of rubbish we produce and encourage people to reuse and recycle. We also need to have a strict punishment for those who throw rubbish (4) ______ the streets, in the ponds, rivers and seas. Besides, we ourselves should raise our environmental (5) ______ by keeping our environment green, clean and beautiful.  1. A. pollution B. polluted C. pollute D. polluting 2. A. because B. so C. therefore D. however 3. A. reduces B. reducing C. reduce D. reduced 4. A. of B. at C. on D. in 5. A. knowledge B. realization C. alertness D. awareness .