Task1 Identify the topic sentence in each of the following paragraphs. 1. The forestis a sanitary agent. It is constantly eliminating impurities from the earth andthe air. Trees check, sweep, and filter from the air quantities of filthy,germ-laden dust. Their leaves absorb poisonous gases from the air. Roots assistin drainage, and absorb impurities from the soil. Roots give off acids, andthese acids, together with the acids released by the fallen, decaying leaves,have a sterilizing effect upon the soil. Trees help to keep the earth sweet andclean, and water which comes from a forested watershed is likely to be pure.Many unsanitary areas have been redeemed and rendered healthy by tree planting. 2. She was anold woman and lived on a farm near the town in which I lived. All country andsmall-town people have seen such old women, but no one knows much about them.Such an old woman comes into town driving an old worn-out horse or she comesafoot carrying a basket. She may own a few hens and have eggs to sell. Shebrings them in a basket and takes them to a grocer. There she trades them in.She gets some salt pork and some beans. Then she gets a pound or two of sugarand some flour. Afterwards she goes to the butcher's and asks for some dogmeat. She never visits with anyone, and as soon as she gets what she wants shestarts for home. 3. The needfor humane studies, both in themselves and for scientists and professional men,is greater than it ever was. In international affairs and in a world where wehave already reached the point where we can annihilate ourselves, the problemthat we face will certainly not be solved by better and better weapons in thehands of opposing armed nations. They will be solved by a better understanding ofmen, by a public educated and enlightened enough to support that diplomacy.Until that solution appears, our governments must continue to arm and todevelop weapons against the idiotic possibility of war, but our only hope of along-term peace comes not from better weapons, but from humane agreementbetween men and nations.