Charles Wortmann at the University of Nebraska-Lincoln says a one-time tillage may be used to correct a problem like aggressive weeds.

VOA: special.2010.09.28

But they can be very aggressive and protective of their territory.

VOA: special.2009.08.19

Vice Chief of Staff, General Peter Chiarelli,said military personnel must be more aggressive in getting treatment for mentally ill soldiers.

VOA: standard.2009.12.25

Some of them have pretty aggressive hardcore ideas, which are unlikely to ever be compatible with American interests.

VOA: standard.2009.03.26

"In preparing for recording and taking those aggressive steps, you have to be one with the spirit, allowing the ebb and flow of the physical and spiritual to become one."

VOA: standard.2010.06.09

But it adds that, even if aggressive policies are put in place to reduce future carbon emissions, steps must be taken now to adapt to greenhouse gases already in the atmosphere;

VOA: standard.2010.06.14