English has two tenses by which verbs are inflected: a non-past tense (present tense) and a past tense (indicated by ablaut or the suffix -ed). What is commonly called the future tense in English is indicated with a modal auxiliary, not verbal inflection.
The following chart shows how TAM (tense/aspect/mood) is expressed in English:
have -ne (perfect)
be -ing (progressive)
Because will is a modal auxiliary, it cannot occur with other modals, such as can, may, and must. Only aspects can be used in infinitives ("to have talked": perfect aspect; "to be talking": progressive aspect).
Grammarians and linguists typically consider will to be a future marker and give English two non-inflected tenses, a future tense and a conditional, marked by will and would respectively. In general parlance, all combinations of aspects, moods, and tenses are often referred to as "tenses".
The distinction between grammatical tense, aspect, and mood is fuzzy and at times controversial. The English continuous temporal constructions express an aspect as well as a tense, and some therefore consider that aspect separate from tense in English. In Spanish the traditional verb tenses are also combinations of aspectual and temporal information.
Going even further, there is an ongoing dispute among modern English grammarians (see English grammar) regarding whether tense can only refer to inflected forms. In Germanic languages there are very few tenses (often only two) formed strictly by inflection, and one school contends that all complex or periphrastic time-formations are aspects rather than tenses.
[VERB] + s/es in third person
USE 1 Repeated Actions
Use the Simple Present to express the idea that an action is repeated or usual. The action can be a habit, a hobby, a daily event, a scheduled event or something that often happens. It can also be something a person often forgets or usually does not do.
She always forgets her purse.
USE 2 Facts or Generalizations
The Simple Present can also indicate the speaker believes that a fact was true before, is true now, and will be true in the future. It is not important if the speaker is correct about the fact. It is also used to make generalizations about people or things.
California is in the west coast of America.
USE 3 Scheduled Events in the Near Future
Speakers occasionally use Simple Present to talk about scheduled events in the near future. This is most commonly done when talking about public transportation, but it can be used with other scheduled events as well.
The last bus leaves tonight at 6 PM.
USE 4 Now
Speakers sometimes use the Simple Present to express the idea that an action is happening or is not happening now.
He needs his medicine immediately.
[am/is/are + present participle]
USE 1 Now
Use the Present Continuous with Normal Verbs to express the idea that something is happening now, at this very moment. It can also be used to show that something is not happening now.
They are having their lunch.
USE 2 Longer Actions in Progress Now
In English, "now" can mean: this second, today, this month, this year, this century, and so on. Sometimes, we use the Present Continuous to say that we are in the process of doing a longer action which is in progress; however, we might not be doing it at this exact second.
I am studying to become a doctor.
USE 3 Near Future
Sometimes, speakers use the Present Continuous to indicate that something will or will not happen in the near future.
I am meeting some friends after work.
USE 4 Repetition and Irritation with "Always"
The Present Continuous with words such as "always" or "constantly" expresses the idea that something irritating or shocking often happens. Notice that the meaning is like Simple Present, but with negative emotion. Remember to put the words "always" or "constantly" between "be" and "verb+ing."
He is constantly talking.
[VERB+ed] or irregular verbs
USE 1 Completed Action in the Past
Use the Simple Past to express the idea that an action started and finished at a specific time in the past. Sometimes, the speaker may not actually mention the specific time, but they do have one specific time in mind.
Last year, I didn't travel to Korea.
USE 2 A Series of Completed Actions
We use the Simple Past to list a series of completed actions in the past. These actions happen 1st, 2nd, 3rd, 4th, and so on.
I finished work, walked to the beach, and found a nice place to swim.
USE 3 Duration in Past
The Simple Past can be used with a duration which starts and stops in the past. A duration is a longer action often indicated by expressions such as: for two years, for five minutes, all day, all year, etc.
Shauna studied Japanese for five years.
USE 4 Habits in the Past
The Simple Past can also be used to describe a habit which stopped in the past. It can have the same meaning as "used to." To make it clear that we are talking about a habit, we often add expressions such as: always, often, usually, never, when I was a child, when I was younger, etc.
I studied French when I was a child.
USE 5 Past Facts or Generalizations
The Simple Past can also be used to describe past facts or generalizations which are no longer true. As in USE 4 above, this use of the Simple Past is quite similar to the expression "used to."
She was shy as a child, but now she is very outgoing.
[was/were + present participle]
USE 1 Interrupted Action in the Past
Use the Past Continuous to indicate that a longer action in the past was interrupted. The interruption is usually a shorter action in the Simple Past. Remember this can be a real interruption or just an interruption in time.
I was watching TV when she called.
USE 2 Specific Time as an Interruption
In USE 1, described above, the Past Continuous is interrupted by a shorter action in the Simple Past. However, you can also use a specific time as an interruption.
At midnight, we were still driving through the desert .
USE 3 Parallel Actions
When you use the Past Continuous with two actions in the same sentence, it expresses the idea that both actions were happening at the same time. The actions are parallel.
I was studying while we was making dinner
USE 4 Atmosphere
In English, we often use a series of parallel actions to describe the atmosphere at a particular time in the past.
When I walked into the office, several people were busily typing, some were talking on the phones, the boss was yelling directions, and customers were waiting to be helped. One customer was yelling at a secretary and waving his hands. Others were complaining to each other about the bad service.
USE 5 Repetition and Irritation with "Always"
The Past Continuous with words such as "always" or "constantly" expresses the idea that something irritating or shocking often happened in the past. The concept is very similar to the expression "used to" but with negative emotion. Remember to put the words "always" or "constantly" between "be" and "verb+ing."
I didn't like them because they were always complaining.
PRESENT PERFECT [has/have + past participle]
USE 1 Unspecified Time Before Now
We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.
People have traveled to the Moon.
The concept of "unspecified time" can be very confusing to English learners. It is best to associate Present Perfect with the following topics:
TOPIC 1 Experience
You can use the Present Perfect to describe your experience. It is like saying, "I have the experience of..." You can also use this tense to say that you have never had a certain experience. The Present Perfect is NOT used to describe a specific event.
I have been to France.
This sentence means that you have had the experience of being in France. Maybe you have been there once, or several times.
TOPIC 2 Change Over Time
We often use the Present Perfect to talk about change that has happened over a period of time.
You have grown since the last time I saw you.
TOPIC 3 Accomplishments
We often use the Present Perfect to list the accomplishments of individuals and humanity. You cannot mention a specific time.
Man has walked on the Moon.
TOPIC 4 An Uncompleted Action You Are Expecting
We often use the Present Perfect to say that an action which we expected has not happened. Using the Present Perfect suggests that we are still waiting for the action to happen.
She has talked to several specialists about her problem, but nobody knows why she is sick.
When we use the Present Perfect it means that something has happened at some point in our lives before now. Remember, the exact time the action happened is not important.
Sometimes, we want to limit the time we are looking in for an experience. We can do this with expressions such as: in the last week, in the last year, this week, this month, so far, up to now, etc.
USE 2 Duration From the Past Until Now (Non-Continuous Verbs)
We use the Present Perfect to show that something started in the past and has continued up until now. "For five minutes," "for two weeks," and "since Tuesday" are all durations which can be used with the Present Perfect.
Mary has loved chocolate since she was a little girl.
PRESENT PERFECT CONTINUOUS
[has/have + been + present participle]
USE 1 Duration from the Past Until Now
We use the Present Perfect Continuous to show that something started in the past and has continued up until now. "For five minutes," "for two weeks," and "since Tuesday" are all durations which can be used with the Present Perfect Continuous.
They have been talking for the last hour.
USE 2 Recently, Lately
You can also use the Present Perfect Continuous WITHOUT a duration such as "for two weeks." Without the duration, the tense has a more general meaning of "lately." We often use the words "lately" or "recently" to emphasize this meaning.
Recently, I have been feeling really tired.
Remember that the Present Perfect Continuous has the meaning of "lately" or "recently." If you use the Present Perfect Continuous in a question such as "Have you been feeling alright?", it can suggest that the person looks sick or unhealthy. A question such as "Have you been smoking?" can suggest that you smell the smoke on the person. Using this tense in a question suggests you can see, smell, hear or feel the results of the action. It is possible to insult someone by using this tense incorrectly.
[had + past participle]
USE 1 Completed Action Before Something in the Past
The Past Perfect expresses the idea that something occurred before another action in the past. It can also show that something happened before a specific time in the past.
She only understood the movie because she had read the book.
USE 2 Duration Before Something in the Past (Non-Continuous Verbs)
We use the Past Perfect to show that something started in the past and continued up until another action in the past.
We had had that car for ten years before it broke down.
Unlike with the Present Perfect, it is possible to use specific time words or phrases with the Past Perfect. Although this is possible, it is usually not necessary.
PAST PERFECT CONTINUOUS
[had been + present participle]
USE 1 Duration Before Something in the Past
We use the Past Perfect Continuous to show that something started in the past and continued up until another time in the past. "For five minutes" and "for two weeks" are both durations which can be used with the Past Perfect Continuous. Notice that this is related to the Present Perfect Continuous; however, the duration does not continue until now, it stops before something else in the past.
James had been teaching at the university for more than a year before he left for Asia.
USE 2 Cause of Something in the Past
Using the Past Perfect Continuous before another action in the past is a good way to show cause and effect.
Sam gained weight because he had been overeating.
If you do not include a duration such as "for five minutes," "for two weeks" or "since Friday," many English speakers choose to use the Past Continuous rather than the Past Perfect Continuous. Be careful because this can change the meaning of the sentence. Past Continuous emphasizes interrupted actions, whereas Past Perfect Continuous emphasizes a duration of time before something in the past.