🔭 Grammar B2-17: Future perfect continuous

The material that closes the perfect-continuous family in the Fleydo grammar series. It opens at the Calder Ridge Observatory on the eve of a twenty-year anniversary: by April, Marit will have been running the survey for twenty years — a sentence written from a point in the future, looking back down the road behind it. The form is taught as four fixed words in which nothing agrees with anything, with a full table of statements, negatives, questions and short answers, and the two shapes of the anchor kept apart: bare by takes a point (by June, by midnight), by the time takes a clause whose verb stays in a present tense. The B2 win is the system view — one table and one three-position timeline slide the same engine, been + verb-ing, along the line: evidence now takes has been doing, a past milestone takes had been doing, a milestone ahead takes will have been doing, and only the front auxiliary ever moves. A four-question decision procedure runs through three worked examples, the third of which is deliberately about register. The compare-and-verdict pair is the heart of the topic: she will have been teaching for twenty years, the run of time celebrated, against she will have taught three thousand lessons, the score counted — duration loves the continuous, totals demand the simple, and a stray number is the trap that catches most learners. A 130-word director’s newsletter note supplies the tap-and-explain text, with the anchors marked in their own colour. Practice runs to thirty-two explained multiple-choice items in four sets, twelve phrases to sort into total and duration boxes, six real learner errors to repair, and five traps — the count in the continuous, the state verb wearing an -ing it refuses, the sentence with no by-anchor to stand on, the will that leaks into a by-the-time clause, and the commonest B2 failure of all: reaching for this rare tense when a plainer future would have been better English.