Future Perfect

Future Perfect 

This is a grammatical structure I have always have troubles with. I can understand the grammatical structures but sometimes it is difficult for me to apply it in context. 

Grammatical Rules 

This is the structure that should be use when talking in future present 

Positive

Subject + will have + past participle 

Subject + to be + going to have + past participle 

Examples:

I will have ended the call by the time I have lunch 

I am going to have eaten fish before I take calls 

Negative 

Subject + will + not + have + past participle 

Subject + to be + not + going to have + past participle

Examples:

I will not have ended the call by the time I need to go home 

I am not going to have finished the troubleshooting before the user´s reunion 

Interrogative 

Will + Subject + have + past participle? 

To be + Subject + going to have + past participle? 

Examples:

Will you have ended the call by the time we have lunch? 

Are you going to have finished the office repair before having breakfast?

Uses 

1. We use the future tense to talk about actions that will be finished before some point in the future 

2. We also use this tense to express situations that will last for an specific priod of time at a dfinite moment in the future 

3. To express certainty that an action was completed