Focusing on the main ideas.In his 2003 speech at Rice University’s Energy & Nanotechnology Conference, the late Nobel Laureate Richard Smalley highlighted the110 problems for the next 50 years. In his list,2sits at the top, and water comes next. Now, with the price of solar power going down, the dawn of a new energy3is just around the corner. As a result,4is going to be the greatest challenge for humanity.But the water problem is5. First, unlike coal and oil, water cannot be6. Second, water is7with every other sector of society. Third, while water demands are growing, climate change is intensifying droughts and floods and water supplies are 8.There are solutions, such as building water-transfer aqueducts, hydroelectric dams, and desalination plants. But they may be incredibly9. It will10for scientists to find affordable solutions to the water problem. Before that, everyone should do his or her bit to11water.