a town planner draws up plans for roads and paths. He/she must think about what car drivers, cyclists and pedestrians need and try to cater for everyone.
the areas around the North and South Poles
anything to do with governments
anything that makes the environment dirty or unpleasant. Cars cause air and noise pollution.
anything that makes the water dirty - such as rubbish, chemicals, untreated sewage and oil
things which make the river dirty such as chemicals, rubbish and sewage
the process of cleaning the water