????9. 太陽能

????今年10月，一輛太陽能汽車以56英里的平均時速在澳大利亞內地行駛了2,000英里。聽起來很完美——太陽能不用花錢，也十分清潔——但有幾點必須注意：這輛由荷蘭人打造的車（見上圖）只載了一名駕駛者，只能在白天行駛，還要用一個小型電池才能開動。這就是未來的汽車嗎？恐怕不是。用以捕捉陽光并將其轉換為電能的光伏電池生產成本十分高昂，同時這輛車所用的鈦合金這類輕型金屬也非常昂貴。不過，太陽能車如果白天能充電，可能可用來當通勤車，比如有一些現在已用作高爾夫車了。

????9. Solar

????In October, a car powered by the sun drove almost 2,000 miles across the Australian outback at an average speed of 56 miles per hour. Sounds perfect -- solar power is free and clean -- but there are a few caveats: The Dutch-engineered car (above) just carried a driver, travelled only during daylight hours, and used a small battery to get rolling. Is this the future? Probably not. The photovoltaic cells that capture the sunlight and convert it to electricity are expensive to produce, and the car is made from pricey lightweight materials like titanium composites. However, solar-powered vehicles might find limited use as commuter cars where they had an opportunity to recharge during the day, and some are used today as golf carts.