A couple of years ago, those who forecast that oil price would reach $ 100 a barrel were seen as doomsters. However, now some are predicting $ 200 a barrel. Had economists been told that oil price would barely pause at $ 100 before reaching the recent peak of nearly $ 127, they would no doubt have forecast terrible economic consequences. But the global economy, though interrupted by the high price of energy, is still chugging along. Meanwhile, inflation has picked up, but the headlinerates of inflation  in most developed countries are nowhere near the levels seen in the 1970s and 1980s. There are three explanations for the oil price's unclear impact. The first is that nowadays developed economies are more efficient in their use of energy, thanks partly to the increased importance of service industries and the diminished role of manufacturing . According to the Energy Information Administration, the energy intensity of America's GDP fell by 42% between 1980 and 2007. A second theory is that the oil-price rise has been steady, not sudden, giving the economy time to adjust. Giovanni Serio of Goldman Sachs points out that in 1973 there was a severe supply shock because of the oil embargo , when the world had to cope with 10%-15% less crude almost overnight. Not this time. The third explanation turns the argument on its head; rather than oil harming the global economy, it is global expansion that is driving up the price of oil. The most important factor is the shift in favor of the developing economies. America has responded to high price in familiar fashion: UBS forecasts that demand will drop by 1.1% this year and will be no higher in 2010 than it was in 2004. But the demand from China and other emerging markets is more than offsetting  this shortfall. What is the passage mainly talking about?
The prediction of economists. The situation of economy The increase of oil price The American response to high price