About writing

Date: 2015-10-07; view: 486.

When you write a text, it is usual to make the topic of the text very clear to your reader. This is done by stating the topic in a prominent position in the text, most frequently in the first sentence. A sentence which states the topic of a text, or of a paragraph or group of paragraphs, is called a topic sentence. (Sometimes this is known as the thesis sentence.)

Study the following text and diagram, then:

a) underline the topic sentence of paragraph 1;

b) complete the topic sentence of paragraph 2;

c) write a third paragraph beginning with this topic sentence:

'Bilharzia could be eradicated.'

1. Bilharzia is a disease found all over the world. It is spread by a small fluke, or flatworm (called schistosoma) which lives as a parasite in the water snail during one stage of its life-cycle, and in man during another stage. Three species cause human disease: one is found in parts of Africa, Spain and the Middle East, another in Africa and Central/South America and the last in the Far East. In these areas schistosoma eggs are present in slow-moving water.

Worms leave snail, pass into water.

Worms enter man.

Wo r m s ch a n g e f o r m and increase in number.

Worms enter snail.

Worms leave body, pass into water.

The life-cycle of schistosoma, the parasite causing bilharzia

2. The life cycle of schistosoma.......................................................................................................

The first stage takes place in the water. When the eggs hatch, the embryoes enter the bodies of water snails. They develop into worms inside the snails. Eventually the worms return to the water, and penetrate the skin of any person who happens to be standing in the water. Once inside the human body they move through the blood vessels to the liver. They remain in the liver until they are adult, and then move to the bladder, where they lay their eggs, causing severe inflammation. Finally the eggs are excreted into the water, and the cycle begins all over again.

Two common types of topic sentence are:

1 the generalization:
'Bilharzia is a disease found all over the world.'

2 the preview:

'The life cycle of schistosoma can be divided into two stages.'