tenses

Present simple

I work

• talking about a truth, fact, permanent situation

• Talking about a habit, repeated actions

• Talking about a series of actions

Present continuous

I am working

• Talking about things that are true now

• Talking about repeated actions in a temporary fixed time
  Talking about a series of ongoing actions

Past simple

I worked

• Talking about single completed actions

• Talking about a series of actions in the past

• Talking about repeated actions in the past

Past continuous

I was working

• Talking about an ongoing action in the past
  Talking about a temorary situation in the past

• Talking about the states of a process of change in the past

Present Perfect

I have worked

• Talking about an action that started in the past and is continuing in the present

• Talking about an action that happened in the past and may happen again

• Stressing present result

Present Perfect Continuous

I have been working

• Talking about an action that started in the past that is still continuing, with stress on duration.

• Talking about an action that started in the past and is still continuing, stress on ongoing nature

• Talking about an action that started in the past that just finished or is still continuing, with stress on activity itself

Past perfect simple

I had worked

• Talking about actions that take place before another action in the past

• Talking about past intentions that weren’t fulfilled

Past Perfect continuous

I had been working

• Talking about actions which continued up to or stopped just before a time in the past

• Talking about a past habit

• Talking about a past state

• Talking about being accustomed to something

Future simple

I will work

• Talking about an instant decision

• Talking about a prediction based on guesswork

Future continuous

I will be working

• Talking about predictions about temporary actions which expect to be in progress at a particular point in the future.

• Talking about events that are the result of or part of an arrangement made in the past

• Talking about events that we see as certain because they are part of a routine

Future perfect

I will have worked

• Talking about predictions about actions which we expect to be completed by a particular time in the future.

Be going to

It is going to work

• Talking about an intention

• Talking about a prediction based on evidence in the present