1.The low cost of installing solar water heaters, together with no cost of water energy consumption, gives rise to its popularity in China. _______ 2. Solar water heaters are common to be seen on the roofs of many households in China. _______ 3. Beijing aims to popularize solar water heaters from 114 million square meters to 300 million by 2020. _______ 4. Some Americans are wondering why solar water heaters are not so popular as in China. _______ 5. Solar water heaters could be popular in some parts of the world if they were sold at an affordable price. _______ 6. Solar collectors are not common in America because of the high cost. _______