27. People have become aware ______the fact that carbon dioxide, poison to the environment, contributes_____ air pollution.
—Look! Someone ________ the floor.—Well, it wasn't me. I went shopping just now.
It's said that they ________ a better life ever since they moved to the US.
—Ouch! You hurt me.—I'm sorry. But I ________ any harm. I ________ to drive a rat out.
In general, most tennis ________ on hard courts or on clay.
Despite ongoing street protests, US beef ________ in South Korea due to its lower price.