Last Monday our class went on a(n)(organize) trip to a forest to study the wildlife. We planned to have our picnic lunch in the forest next to a(n)(fall)tree, but the terrible smell given off by a (pollute) river made us feel sick. We searched the forest for the polluter (污染源), and found an unknown factory (pour) waste water into the river. We all thought it was a serious problem and one solution (suggest) by our class was to close the factory as soon as possible.
