"We must have received..." and "We probably received..." both should be accepted, because (according to the Big Red Book of Spanish Verbs) the future perfect tense is also used to express a conjecture or guess about what happened in the past.
We will all have lost the will to live by the time Duo's database has caught up with these nuances.
Kamelot, By the time you read this comment, you will have completed the tree. A perfectly good sentence, but maybe not true :-)
Is this "will have" same as the hypothetical "would have"? English isn't my first language and I have not encountered the use of "will have + participle " prior to this exercise.
No, they are not the same. "Will have" is future perfect and "would have" is conditional perfect. Not sure what your first language is. (Is it Spanish?) Either way, if you want to read something more detailed on this topic, the following should qualify:
If you want to specifically focus on future tense, skip to this section here:
As you can see from the title of the page, its purpose isn't to expound on the future perfect and the conditional perfect, but it contains some examples in it that might clear some expressions up for you should you see them in the future. If your post is anything to go by, your English appears to be quite good, but be forewarned. This page on "shall" and "will" could confuse even a native speaker of English, despite the fact that it is well written.
Hope that takes your English (and Spanish) to another level. Speaking of which, you may want to skip any of my previously recommended links and just check out the following:
This was why I got it wrong at first. Would a male voice saying this sentence make sense? Or should I not assume that this voice belongs to a man? Gripes.
Gary, your sentence expresses obligation in the future. Future perfect expresses an action in the future that will already have happened by the time some other action takes place. Eg: If I continue to save money, when I retire (or by the time I retire), I will have saved enough for a long cruise. Neither event has happened yet. Hope this helps.
I am getting heartily fed up with listening at speed and clearly hearing "nosotros" and finding on the slower recording a far more distinct "nosotrAs". And, what regional accent makes "ellos" sound like "elloos". Is it just me, or are there others out there finding this?