52 Science Research Writing KEY Th e nouns which can also have a countable meaning appear in italics. life luck philosophy nature loss paper organisation pollution physics oil power progress research protection policy pressure reality security respect purity rain sand strength silence safety salt science time stuff sleep swimming space trouble trade sunlight transport technology waste truth traffi c vision treatment water velocity violence wildlife wind work wealth welfare absence access analysis advice age agriculture cancer art atmosphere beauty behaviour duty capacity childhood calculation concern economy death democracy depression design environment earth education electricity energy evidence equipment existence experience failure fashion fear fi re health food freedom history growth independence heat help insurance ice knowledge industry information machinery intelligence light life luck philosophy nature loss paper organisation pollution physics oil power progress research protection policy
Methodology — Grammar and Writing Skills 53 Now look at the second problem: how do you decide whether to use a or the? You may have been told that a is used for general reference and the is used for specifi c reference, but in the following sentence: Th ere is a book on the shelf above my desk; can you bring it here? a book clearly refers to a specifi c book; in fact, that part of the sentence specifi es which book the speaker wants. So if the specifi c/general criterion doesn't help you to select a or the, what does? Start by asking yourself this simple question: Why do you use a the fi rst time you talk about something, but when you refer to it again you use the? Aft er all, it's the same specifi c item on both occasions. For example, in the sentence below, why does the fi rst reference to the cheese sandwich use a and the second reference use the if both refer to the same specifi c sandwich? I had a cheese sandwich and an apple for lunch. Th e sandwich was fi ne but the apple had a worm in it. Th e diff erence is that the fi rst time the speaker mentions the cheese sandwich or the apple, only the speaker knows about them — but the second time, both the speaker and listener know. Th e worm, however, is 'new' to the listener, and so is referred to using a. Now we can add a new rule: pressure reality security respect purity rain sand strength silence safety salt science time stuff sleep swimming space trouble trade sunlight transport technology waste truth traffi c vision treatment water velocity violence wildlife wind work wealth welfare USE THE IF OR WHEN YOU AND YOUR READER BOTH KNOW WHICH THING/PERSON YOU MEAN.