Hydrogen is an alternative energy source with high efficiency and pollution free.

氢能是高效、环保型替代能源。

youdao

Huabao is a pollution free insecticide which has strong contact poisoning function on aphids, cicadas, mites and scales.

花保是一种无公害的触杀剂，对多种刺吸式口器害虫如蚜虫、蝉、红蜘蛛、介壳虫等有较强的触杀作用。

youdao

The results show that the flocculants have strengths such as low cost, easy preparation, non-toxic, pollution free and good flocculation results.

结果表明，上述絮凝剂具有成本低、工艺简单、无毒、无污染、净水效果好等优点。

youdao

And the dymaxion car -- which could have provided safe, pollution-free transportation using little gasoline -- was never produced.

VOA: special.2010.05.30

Caviar produced in the Sologne, a rural, pollution-free region of central France, has found fans among French chefs.

WSJ: Black Gold: French Caviar Is �� la Mode

President BUSH: We will increase our research in better batteries for hybrid and electric cars and in pollution-free cars that run on hydrogen.

NPR: Slate's Politics: State of the Union Specifics

The river was nearby, clear and free of all pollution, and petrol was easy to obtain, in unlimited quantities, from the filling stations and parked cars.

NEWYORKER: The Autobiography of J.G.B.