1. Fill in the blank with a word/ phrase in the box. sources believe renewable solar and wind power supplying energy It's hard to (1) that just 200 years ago our main energy source was wood. Now we have a wealth of energy sources to choose from, including a growing range of (2) energy technologies. But what does the future hold? How can we keep (3) to an ever- growing population? How much will it cost? And what impact will the energy choices we make have on our living conditions and our planet? In a report this year, the International Energy Agency expects electricity generation from renewable energy (4) to increase from 21 percent in 2012 to 33 percent by 2040. Moreover, as battery technology improves, it will be better able to support renewable energy sources, such as (5)