The Tenses of the English language often causes the most confusion amongst students.
For more details and examples have a look at the individual posts with regards to each of the twelve tenses in English. In this post we have simplified it.
To determine which tense should be used, ask a question and then see what information is required.
For example: Question: Do you work?
CONTINUOUS at what time?
PERFECT by what time?
PERFECT CONTINUOUS since what time/how long?
Present simple: I do (usually, often, always) I work every day
Present continuous: I am doing(now) I am working now
Present perfect: I have done (never, ever, just, already) I have already worked
Present perfect continuous: I have been doing(since/for)I have been working since yesterday
Past simple: I did (yesterday, last year, long ago) I worked yesterday
Past continuous: I was doing (yesterday at 3pm) I was working yesterday at 3pm
Past perfect: I had done (yesterday by 3pm) I had worked by 3pm
Past perfect continuous: I had been doing I had been working since 3pm
Future simple: I will do (tomorrow, next week) I will work tomorrow
Future continuous: I will be doing (tomorrow at 3pm) I will be working tomorrow at 3pm
Future perfect: I will have done (tomorrow by 3pm) I will have worked tomorrow by 3pm
Future perfect continuous: I will have been doing I will have been working for 6 hours