The past tense of regular verbs is formed by adding -d or -ed. For example, the present tense I smile becomes the past tense I smiled. They want becomes they wanted. Most verbs are regular verbs.

Irregular verbs do not follow the same pattern. To change the tense of an irregular verb, you do not add -d or -ed. The base form might not change at all, it might take a spelling change other than the addition of -d or -ed, or it might change only its pronunciation. See Chapter 6, pages 137-143, for more discussion on regular and irregular verbs and for a list of common irregular verbs.

Exercise 1.5

For the following sentences:

(a) Write s over the key word or words in the subject.

(b) Write υ over the verb or verb phrase. (Create you own marking system to show that an element contains more than one word.)

(c) Label other structurally important elements in the predicate—if there are any—with sub com, ob com, do, and io.

1. According to a recent study, even mild sleep deprivation can prevent the retention of new and complex knowledge.

2. For centuries, the tongue, with its various colors, textures, and patterns, has given doctors a mirror of the condition of the rest of the body.

3. By November 1964, Malcolm X had made three trips to Africa and had altered his position on the possibility of black and white cooperation and harmony.

4. Nintendo Power magazine is published every other month.

5. In his later works, Vincent van Gogh painted his suns a brilliant yellow.

6. Competition has been defined as mutually exclusive goal attainment.

7. Perhaps Chester F. Carlson should have named his invention, the copying machine and forerunner of the Xerox machine, after himself.

8. Standard male mannequins wear size 40 regular.

9. Since the beginning of the last Ice Age, the size of human teeth has been decreasing at the rate of one percent every two thousand years.

10. According to experts in nutrition, most people with occasional mood swings should blame their diet, not their ancestry or sheer bad luck.