To make dirty or foul; pollute.

弄脏或使污秽；

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To defile means to make dirty or impure.

玷污就是弄脏，使一个人变得不纯洁。

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Reeds can absorb masses of pollutants to make dirty water clean.

芦苇能吸收大量的污染物从而净化污水。

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The first thing the coalition plans to do is make "dirty" energy more expensive.

BBC: Who pays for UK coalition's 'green economy'?

"We've got to be better, go to the dirty areas, make it hard, make it so he can't get out of his crease, " said Rangers defenseman Ryan McDonagh, whose delay-of-game penalty in overtime led to the winning goal.

WSJ: Holtby, Caps look to build on lead over Rangers

Mr. STEVE HINCHMAN (Conversation Law Foundation): And as consumers realize, they have a choice to buy a clean car that's 20 to 50 percent more efficient, we're going to hit a tipping point where it will no longer make economic sense for Detroit to continue making the dirty version of the car.

NPR: States Push Automakers on Fuel Efficiency