smog = dirty air
crowded = full of people
advantage = good thing, positive point
disadvantage = bad thing, negative point

Do you know why the color of the sky is brown? It's the ___ from all cars and factories

I don't like to take the bus at 5:00 in the afternoon. It's always ___ with so many people coming home from work

Winter in Canada is very cold, but there is also an ___ there are great places to ski

Patrick wants to work in the United States. His big ___ is that he doesn't speak English

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