Language Point 25

Natural gas, an outstanding energy fuel, can be used to heat homes, make electricity, and power cars. (Para. 12)

Meaning: Natural gas, which is an exceptional energy fuel, can be used to provide heat for homes, electricity, and even power for cars.

Notice that the phrase "an outstanding energy fuel" is an appositive（同位語）.

outstanding: a. well-known; important

Students with outstanding university records may win scholarships. 學業成績優秀的大學生可獲獎學金。

Professor Cary has a name as an outstanding lecturer. His classes are always well attended. 卡里教授上課之精彩是出了名的，他的課總是吸引著許多學生。