—We must try tosavehim.
—Let me help you.
—Sorry. We're out of stock (缺货) now. We willproducemore later.
—OK. We need more ideas.
—I'm worried about the crops. Too much rainis harmful tothem.
—I also want to have a penfriend.
—Because he thinks it is stupid.
—Yes. It's very ________.
—That's true. It has become one of the biggest killers of men.
—Yes. They can ________ harmful gases from the air.
—They provide us ________ wood, fruit and so on.