Have you read the book called Uncle Tom's Cabin? It's said that it is one of the greatest books in America．The book an unpleasant social problem—slavery(奴隶制)in the Southern States of America. It first came out in 1852．Over 300,000were sold out in a year．People had ideas about the book．In the North, more and more people began totheft support(支持)for the freedom(自由)for the black people after they read the book, but in the South, many people were veryat the people in the North. In 1861, the war between the two parts of the country. Uncle Tom's Cabin surely played a part in the . In 1862, Abraham Lincoln met Harriet Beecher Stowe, the book's . As he took her hand. Lincoln said, "So this is the little lady who started this big war."

— No, ________ he has finished his homework.

— I'll be glad to help her, ________ needs some help.

— It will get worse ________the government does something about the pollution.

— Yes, ________ he is in charge of the office, he must be there.