Read the following sentences.
- She will finish the job. When? By the end of this month.
We can combine these two.
- She will have finished the job by the end of this month.
Note that we use the future perfect tense to say that somebody will have done something by a certain time in the future.
- The children will reach home. When? By the time their father returns from work.
- The children will have reached home by the time their father returns from work.
Exercise
Combine the following pairs by changing them into the future perfect tense.
1. The children will eat all the cake. (before their mother comes.)
2. The fire will destroy the whole building. (before the firemen arrive)
3. The patient will die. (before they reach the hospital)
4. He will leave. (before you reach his place)
5. We will pay back all our debts. (before we leave this city)
Answers
1. The children will have eaten all the cake before their mother comes.
2. The fire will have destroyed the whole building before the firemen arrive.
3. The patient will have died before they reach the hospital.
4. He will have left before you reach his place.
5. We will have paid back all our debts before we leave this city.
Notes
When the main clause is in the future tense, we use a present tense in the subordinate clause to refer to the future.
The patient will have died before they reach the hospital. (NOT The patient will have died before they will reach the hospital.)