6. In talking, follow the plan explained in [Exercise 140], being especially careful in conclusion to summarize the proofs that you have presented.
The conclusions that you reach in your arguments must be based upon statements that are true. In the following, some of the statements are false, and therefore the conclusions based upon them are false. Point out wherein the falsity consists. In others of the following, irrelevant matter has been introduced. Point it out, explaining why it is irrelevant.
1. We shall forget a great many facts that we learn at school. Therefore it is useless to learn them.
2. Oil should be used instead of water in sprinkling our streets, because oil does not evaporate so quickly as water, and so does not allow the dust to rise. Moreover, as the street must be cleaned before the oil is laid, there is less dust to rise. When the oil lies on the streets, it is very sticky, and clings to everyone's shoes. In this way it is tracked into the houses and stores, making everything dirty. Therefore I think the streets should be oiled instead of being watered.
3. Half of the keys would not work on the typewriter that I used yesterday. This machine will work no better, as it is made by the same company.
4. Last year September was very warm, and the winter was extreme. This year September has been very warm, and therefore the winter will be extreme.
5. My cousin never went to high school, and when he went to work he earned eight dollars a week. I have gone to high school for one year. Therefore I shall receive more than eight dollars a week when I go to work.
6. When you are working, your employer will never ask you the definition of a noun. Therefore it is unnecessary to know any grammar.
7. Every one should be punctual in doing his work. If he is punctual, he will be promoted and earn a larger salary. Money is a very important item in this world, but it is not everything. A person must be satisfied with his work so that he can do it cheerfully; otherwise he will not succeed. Therefore I think every one ought to be on time.