填空题
A．over the past 50 years
B．beneath the earth's surface
C．by more than 50 percent
D．for more than four decades
| E．as a raw material F．for home energy
needs |
填空题
Natural gas is stored deep______．
填空题
Natural gas is recognized as the most economical energy source______．
填空题
When manufacturing many different products，people commonly use natural gas______．
填空题
It is estimated that by 2025 the natural gas demand in the United States will increase______．