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独 家 制 作shenchengfei@ QQ：1223317581 TPOOOO 版本：V1.09WToefl Practice Online of Our Own Toefl iBT Practice TestTPO 9 Writing Task 1 No. of Questions: 1 Begin Test Time: approx. 30 minutes CONTINUE Now put on your headset Click on CONTINE to go on Begin reading You have 3 minutes to read the passage. Click to begin reading now . Car manufacturers and governments have been eagerly seeking a replacement for the automobiles main source of power, the internal-combustion engine. By far the most promising alternative source of energy for cars is the hydrogen-based fuel-cell engine, which uses hydrogen to create electricity that, in turn, powers the car. Fuel-cell engines have several advantages over internal-combustion engines and will probably soon replace them. One of the main problems with the internal-combustion engine is that it relies on petroleum, either in the form of gasoline or diesel fuel. Petroleum is a finite resource; someday, we will run out of oil. The hydrogen needed for fuel-cell engines cannot easily be depleted. Hydrogen can be derived from various plentiful sources, including natural gas and even water. The fact that fuel-cell engines utilize easily available, renewable resources makes them particularly attractive. Second, hydrogen-based fuel cells are attractive because they will solve many of the worlds pollution problems. An unavoidable by-product of burning oil is carbon dioxide, and carbon dioxide harms the environment. On the other hand, the only byproduct of fuel-cell engines is water. Third, fuel-cell engines will soon be economically competitive because people will spend less money to operate a fuel-cell engine than they will to operate an internal-combustion engine. This is true for one simple reason: a fuel-cell automobile is nearly twice as efficient in using its fuel as an automobile powered by an internal-combustion engine is. In other words, the fuel-cell powered car requires only half the fuel energy that the i