English past

1. Use of the present perfect

The English Present Perfect tense is used to express actions which have already been completed, or perfected, at the time of speaking or writing. In the examples given below, the verbs in the Present Perfect tense are underlined.
e.g. I have done the work.
She has answered half the questions.

In the first example, the use of the Present Perfect tenseemphasizes the fact that, at the time of speaking or writing, the work has already been completed. In the second example, the use of the Present Perfect indicates that, at the time of speaking or writing, half the questions have been answered.
 
2. Formation of the present perfect: Regular verbs

The Present Perfect tense of any English verb is formed from the Simple Present of the auxiliary to have,followed by what is generally referred to as the past participle of the verb.

Most English verbs form the past participle in a regular, predictable manner. These verbs are commonly referred to as regular verbs.

The past participle of a regular English verb is formed by adding the ending ed to the bare infinitive of the verb. For instance, the past participle of the verb to work is worked.Thus, the Present Perfect tense of the verb to work is conjugated as follows:
I have worked |
you have worked |
he has worked |
she has worked |
it has worked |
we have worked |
they have worked |

See Exercise 1.

The following contractions are often used in spoken English:

Without Contractions | With Contractions |
  I have |   I've |
  you have |   you've |
  hehas |   he's |
  she has |   she's |
  it has |   it's |
  we have |   we've |
  they have |   they've |

It should be noted that the contractions for he has, she has and it has are the same as the contractions for he is, she is and it is.

See Exercise 2.
 
3. Spelling rules for adding ed to form the past participle

Some regular verbs change their spelling when the ending ed isadded to form the past participle.

a. Verbs ending in a silent e
When a regular verb ends in a silent e, only the letter d must be added in order to form the past participle. For example:
Infinitive | Past Participle |
  to close |   closed |
  to move |   moved |
  to please |   pleased |
  to receive |   received |

b. Verbs ending in y
When a regular verb ends in y immediatelypreceded by a consonant, the y is changed to i before the ending ed is added. For example:
Infinitive | Past Participle |
  to study |   studied |
  to rely |   relied |
  to carry |   carried |

However, when a regular verb ends in y immediately preceded by a vowel, the y is not changed before the ending ed is added. For example:
Infinitive | Past Participle |
  to play |   played |  to convey |   conveyed |
  to enjoy |   enjoyed |

See Exercise 3.

c. Verbs ending in a single consonant preceded by a single vowel
The rules concerning the doubling of final consonants which apply when adding the ending ing to form the present participle also apply when adding the ending ed to form the past participle.

Thus, when a one-syllable verb ends in a single consonant otherthan w, x or y immediately preceded by a single vowel, the final consonant must be doubled before the ending ed is added to form the past participle. In the following examples, the consonants which have been doubled are underlined. For example:
Infinitive | Past Participle |
  to rub |   rubbed |
  to trim |   trimmed |
  to plan |   planned |
  to stop |   stopped |

When a verb ofmore than one syllable ends in a single consonant other than w, x or y immediately preceded by a single vowel, the final consonant is doubled before the ending ed only when the last syllable of the verb is pronounced with the heaviest stress. In the following examples, the syllables pronounced with the heaviest stress are underlined. For example:
Infinitive | Past Participle |
  to control |  ...