Overpopulation is one of the most dangerous issues that the human race 1.______ nowadays. The world population 2._____ in the last 50 years, 3. _____ from 3 billion in 1960 to 7 million in 2010. Overpopulation is partly caused by human advancement, especially 4. ____ the medical field. Average life expectancy is higher than ever; people now live longer and healthier. Poverty is also a contributing factor. Researchers show that there is a direct link between overpopulation and poverty. 5._____ and developing countries usually have the highest population growth rate. The lack of education and family planning is often why the population in these countries grows fast 1. A. faces B. is facing C. faced D. will face 2. A. has decreased B. has stood still C. has tripled D. has doubled 3. A. going B. gone C. to go D. go 4. A. at B. in C. over D. within 5. A. Nevertheless B. Once C. Poor D. Luckily