By 2020, the number of schools in our country double.
Note: Future perfect is always used with past participle of a verb indicating a sense of completion of the task on looking back at the activity from some point further in future.
Will + subject + have + past participle…? We'll have arrived We won't have arrived Will we have arrived? Here are the exceptions: 1 One 'e' at the end of a verb Add 'd' at the end of the base form.