Future Perfect Continuous. Use #1 : Duration Before Something in the Future
Future perfect continuous has two different forms: “will have been doing ” and “be going to have been doing.” Unlike simple future forms, future perfect continuous forms are usually interchangeable.
We use the future perfect continuous to show that something will continue up until a particular event or time in the future. “For five minutes,” “for two weeks,” and “since Friday” are all durations which can be used with the future perfect continuous. Notice that this is related to the present perfect continuous and the past perfect continuous; however, with future perfect continuous, the duration stops at or before a reference point in the future.
Example: They will have been talking for over an hour by the time Thomas arrives.- Они будут разговаривать более часа, к тому времени, когда приедет Томас.
Example: She is going to have been working at that company for three years when it finally closes.- Она будет работать в этой компании в течение трех лет, когда она, наконец, закроется.
