I do prepare for the TOEFL myself..I think your text is quite good, however I think I found some mistakes.
Do you agree or disagree with the following statement: The most important problems in today's world will be solved in our lifetime.
Today’s world's most important problems are limited to conventional sources, Terrorism, Global warming, population control. Scientist and researchers have already started working on it and solve such problems. I think these problems will be solved in my life time.
Firstly, today most of the machine, automobiles work_ on conventional energy sources. They are limited on earth. On the other hand dependence on such fuels is increasing. Scientist are inventing unlimited, natural and pollution free sources of energy. Like the use of wind, tidal or solar energy. They convert non renewable energy into electricity. But today the cost of such converting equipments are very high. So considering national and global support for research in this field, I think energy problem will be solved and under control in coming years.
Secondly, Terrorism is today’s evil in society. With social awareness, abandoning such people from society, strict action against terrorist will help to minimize these things. For example, US attacked Pakistan to kill notorious terrorist Osama Bin Laden.
Thirdly, the problem of (over?)population. China has already started dealing with control over population. They offer policies and government aids, free education for single childs of parents. Today the rate of children per parents have came down to 2 from an earlier average rate of 5-6. People are more aware of the effects of population and competition for food and home. In coming days this problem will be under control.
The forth problem is Global Warming. All nations have already united to deal with Global Warming. Emission of green house gasses is a major cause today. But scientists are trying to minimize this rate and hence try to reducing rate of global warming.
In summary, Human being is known for the best example of adaptation. Today’s problems will be solved in coming years and new problems may occur, but scientist and leaders will again try to solve tomorrow’s problems because it’s a human nature.