1. Somsak acted  a guide for the tourists from Singapore.
2. We can define air pollution  an unacceptable level of noxious substances in the air.
3. Chaiwat went to the United States  study law.
4. Though he had many pressing duties, Martin agreed to serve  club president for another term.
5. Williams went to the police station  report a crime.
6. Many regard Beethoven  the greatest composer who ever lived.
7. Mary performed  a dancer in the play  please her mother.
8.  serve their country, some people spend time  soldiers, others,  Peace Corps Volunteers.