1. 3. Verb Forms and Tenses

2. Three important forms
Verbs in English have different forms which are used in the construction of tenses.
Three of the most important forms of any verb are
the base form: the “name” of the verb (e.g. be)
the past tense form: used in the simple past tense
(to be discussed in just a minute)
the past participle form used in perfect tenses (to be discussed in just two minutes!)

3. The base form
The base form of the verb is the “dictionary listing” form, e.g. be or have.
Most verbs also use the base form as one of the present tense forms of the verb
for instance, have is not only the base form of the verb but also a simple present tense form.

4. The past tense and past participle forms
Fortunately, most English verbs have a single form that is used as both the simple past tense and also the past participle forms. In the case of regular verbs, this is the -ed form. For example - the the past form of alarm is alarmed. The lion’s roar alarmed the child. - the past participle form is also surprised. The lion’s roar has alarmed several adults, too. The parents comforted their alarmed child.

5. The past and past participle forms 2
A number of irregular verbs also have the same past tense and past participle form. These irregular forms are unpredictable and must be learned by heart. For example, the past tense of sweep is swept. She swept the floor thoroughly. The past participle form of sweep is also swept. The floor has been thoroughly swept. The swept floor made the room look much more inviting.

6. Simple present and past tenses
Simple Present: used to show actions, states or events that are true in general
Water boils at 100C.
Also used to show habits.
I drink coffee but Sarah drinks tea.
Simple Past: Used to express an action, event, or state occurring at a time in the past.
The time can be general or specific.
I wanted a muffin. (general)
I wanted a muffin for breakfast this morning. (specific)

7. Progressive present and past tenses
Present Progressive: used to show actions or events in progress at the moment. The event is not finished.
The form is be (present form) + verb-ing
John is looking for a new bike.
We don`t usually use the progressive with non action verbs:
I want a new iPod. NOT I`m wanting a new iPod.
Past Progressive: Used to express an action that was in progress at a time in the past.
The form is be (past form) + verb-ing
She was sleeping when the baby started to cry.

8. Perfect present and past tenses
Present Perfect: used to show actions that started sometime in the past (time is not important).
Some actions may continue in the present time and some may be completed.
The form is have + past participle verb
I have lived in Ottawa for 2 years. (continuing)
She has eaten at that restaurant. (completed)
Past Perfect: Used to express and action that is finished at a time in the past. The time is not important.
The form is had + past participle verb
Tom had finished eating when his friends arrived.

9. Perfect progressive present and past tenses
Present Perfect Progressive: Used to show actions that started sometime in the past (time is not important) and are continuing in the present.
The action is not yet finished.
The form is have + been + verb-ing
They have been working with the government since 2006.
Past Perfect Progressive: Used to show that an action was in progress in the past until another action interrupted it.
Used to tell the duration or length of time of the first event.
The form is had + been + verb-ing
She had been working (in progress) for five hours before she took a coffee break (interruption).

10. Future tenses
Although future tenses are not used frequently in academic writing, they will be covered briefly below.
Simple Future: Used to show that an event will occur at a time in the future.
The form is: will + verb
Valerie will go to Spain next month.
Future Progressive: Used to describe an activity that will be in progress at a time in the future.
There are two forms: will + be + verb-ing
be going to + be + verb-ing
He will be taking a psychology course next month.

11. The form is: will + have been + verb-ing
Future Perfect: Used to express an activity that will be completed before another time or event in the future.
There are two events. The first event is expressed in future perfect. The second event is expressed in simple present.
By the time you read (second event) my , I will have been to Japan (first event).
Future Perfect Progressive: shows an action that will be in progress before another time or event in the future. It emphasizes the duration of the event.
The form is: will + have been + verb-ing
When Professor Jones retires next month, he will have been teaching for 45 years.