Which sentence would be most appropriate?
Next year Anny and I will have been married for 25 years.
Next year Anny and I will be married for 25 years.
(this sentence came out of a grammar book. I had to fill in the gap "Next year Anny and I (to be) married for 25 years.)
1 sounds better
Generally if you say, "will have been," it means that state of being / activity has continued over the period of time mentioned. In this example, the marriage has lasted for 25 years, so you say you "will have been married."
If a particular event (say, a special anniversary vacation) is coming up next year, you'd say, "Next year, Anny and I will be going on vacation for our 25th anniversary."
English does not have a future tense, but some forms involving will, shall, and be going to are labelled as such. See discussion of future forms here. I'll use that terminology here.
Next year Anny and I will have been married for 25 years.
This is referred to as future perfect (see Englishpage.com, USE 2 Duration Before Something in the Future). It has the general form [will have + past participle] or [am/is/are + going to have + past participle].
The use here is to show that something will continue up until another action in the future. Future perfect can also be used to express the idea that something will occur before another action in the future, or show that something will happen before a specific time in the future.
This sentence describes that next year, you will complete a milestone of 25 years of marriage, which is logically what is implied by the exercise.
Next year Anny and I will be married for 25 years.
This is referred to as simple future (see Englishpage.com, USE 4 "Will" or "Be Going to" to Express a Prediction). It has the general form [will + verb] or [am/is/are + going to + verb].
The use here is to express a prediction about the future. Simple future can also be used to suggest that the speaker will do something voluntarily, express a promise, or express that something is a plan.
Simple future refers only to future events, it doesn't tie them to past or present activity.
If someone said this sentence, it would probably be interpreted to mean what is intended in the exercise, but only because that would be the only rational interpretation of its meaning. Technically, though, it would mean something different. It literally means that next year, you will get married and the marriage will then last 25 years.
This is an example of the role that context plays in English. Nobody can predict that a marriage will last 25 years, so the literal meaning wouldn't make sense. Also, English errors and variations are experienced all the time, and the manner in which something is said often conveys more than the actual words. So when a listener hears something, especially something that refers to common aspects of life experience described in commonly used words and phrases, they usually don't parse the words for precise meaning.
They hear the gist of what is said. The word combination might sound odd (dwilbank's answer mentions that 'will be' sounds a little funny to a native English speaker), but people just ignore that and interpret it in the way that makes sense given the context. However, despite the fact that the second sentence would likely be understood, it isn't correct (well more accurately, it is not grammatically correct for the intended meaning and if it is interpreted in a way that is grammatically correct, it doesn't make sense).
The perfect Will have been changes the perspective to a present located in the future, from which present a past is to be viewed reaching back into time. Will be, on the other hand, talks about the future from a time located in the present. This makes will be a jarring choice for your sentence because the adverb of time "next year" places the being married firmly in the future.
Instead, let's place the perspective firmly in the present, by removing every trace of the future aspect from the sentences, and see what that leaves us:
Anny and I have been married for 25 years.
Anny and I are married for 25 years.
It seems much easier now to understand why the first option is preferable. The second option forces us to describe a period that reaches into the past with a verb in the simple present, as if the present is 25 years long. It makes sense instead to use the perfect have been to describe the past from the perspective of a time in the present.
The same is true when we add the future aspect: will have been changes the perspective from today's present to a present situated in the future, from which, when next year arrives, we are going to look back over the preceding 25 years.
The way I see it, the second sentence is wrong if speaking about a state that is on-going for a period of time starting in the past. The second sentence gives up the impression that the action (their marriage) will last for 25 years starting next year.
Consider this:
The Future Perfect expresses the idea that something will occur before another action in the future. It can also show that something will happen before a specific time in the future. It consists of the auxiliary verb will (or shall) to mark the future, the auxiliary verb have to mark the perfect, and the past participle of the main verb.
Most commonly the future perfect is used with a time marker that indicates by when (i.e. prior to what point in time) the event is to occur.
Future Simple cannot be used in this sense. However, it can can express the idea of a general prediction about the future.
So, logically, the first sentence is appropriate and correct.
However, if we are just assuming that by the time next year starts Anny and I will, probably, still be married then the second sentence is also correct. Yet, this adds some disbelief and uncertainty about whether Anny and I are going to be married for 25 years next year.
Now let's look at some examples:
Keep on examining:
Even more:
In terms of Future Perfect Continuous vs Future Continuous the odds are the same as above:
Consider the difference with the Future Perfect and Future Simple as well:
The previous answers are all very good and detailed. But people may still be confused about the use of perfect.
Here is a simple and possibly helpful notion:
Present perfect describes a state at present. That state is a result of actions in the past, but the emphasis is on the completion (perfectness) of these actions. Compare the following sentences:
Past perfect has a similar meaning: a state of completeness that occurred in the past.
Future perfect is less common, but the same idea works here too. It describes a state of completeness that is predicted to occur at a future time:
Now, for perfect continuous, things are somewhat more complex. It describes the state of "something happening continuously". That something is not completed; the "it's happening" state is completed. This can be use in present, fast, and future perfect.
Consider the following sentences:
... Getting to your question: - Next year, we will have been married for 25 years. (We will be in the state of "being married 25 years" - and that state will persist) - Next year, we will be married for 25 years, and have a big party to celebrate that. (Non-perfect is used to describe a forecasted action. When discussing the party, it would be more natural to say "We will be married" than "We will have been married", which is the state. We are not discussing what will happen after the party).
Of course, these are very articulate sentences. Many people don't care about these fine differences and may use simple future for everything. This is arguably correct.
In my opinion, language is for expressing ideas and the most important thing is that the other person understands the idea. Using perfect can help expressing the idea sometimes, and distract or sound inappropriate at other times. You can sometimes choose your style. But in an English language exam, it seems appropriate to use future perfect in this case.
'Will have been married' is the most correct one. 'Will be' sounds a little funny to a native English speaker.
