Course paper on theoretical grammar

How to conjugate the perfect tense

As one of the most confusing tenses in English, the perfect tense takes some practice. It has very particular usage guidelines—especially the present perfect—and it’s closely related to the simple past. 

How to conjugate the present perfect tense

The present perfect tense is used for a few special circumstances, mostly connected to past events that haven’t yet ended: 

• 
  actions started in the past but continue into the present
  
• 
  repeated actions in the past without mentioning when 
  
• 
  past actions, for more emphasis or dramatic effect
  

To form the present perfect tense, add the present conjugation of have before the verb’s past participle. 
has/have + [PAST PARTICIPLE]
I’ve worked here since the beginning.
Macbeth has murdered the king! 
(Macbeth murdered the king! is also correct, but the present perfect makes it sound more dramatic.)

How to conjugate the past perfect tense

When a sentence has two past events, use the past perfect tense, also known as the pluperfect, to show which one happened first. It’s typically used in compound or complex sentences with two clauses to show the order in which they happened. 
For the past perfect tense by adding had before the past participle. 
had + [PAST PARTICIPLE]
I had forgotten about our date until she reminded me.
When our plane finally landed, they had already left the airport.

How to conjugate the future perfect tense

The future perfect tense refers to an unfinished event from a future when it’s already completed. Confused? Say you’re riding your bike on Saturday. By Sunday, you’ll be finished riding your bike. You can say, “My bike ride will have finished by Sunday.” That’s why the future perfect tense is usually used with an expression of time, for context. 
It’s formed by adding the words will have before the past participle. You don’t need to conjugate “have,” because it’s the same no matter what the subject is. 
will have + [PAST PARTICIPLE]
By the time I can vote, I will have graduated already. 
We will have stayed together for twenty-five years in August.