vocab: stop re-teaching a word later in the same session (239 tags)

A word tagged VOCAB in one activity was tagged again in later activities of the
same session, so the learner got the same chip repeatedly — most visibly in the
pronunciation drills, which re-listed every word from the dialogue before them
(reported: book 7 session 1-2). Rule applied: drop a VOCAB whose word was
already tagged in an EARLIER activity of that session. Repeats INSIDE one
activity are kept — those teach distinct senses ('stuck to his finger' vs
'stuck the milk in the fridge', 'shop' as verb then noun). Also dropped chips
for plurals of already-known words in book 7 session 1-2, where the drill
teaches the singular/plural pair rather than new vocabulary. No session lost
all of its vocabulary (verified).

Co-authored-by: Cursor <cursoragent@cursor.com>

book-11-lesson-2.module

@@ -685,7 +685,6 @@ INTRO: Now hear the key traffic words in short sentences, and repeat them after
 INSTRUCTION: Listen and repeat.
 REPEAT
 
-VOCAB: caution
 LINE: Be careful; use caution. {bk11-l2b-f1-01.mp3}
 
 VOCAB: flash
@@ -697,7 +696,6 @@ LINE: Streets cross at intersections. {bk11-l2b-f1-03.mp3}
 VOCAB: pedestrian
 LINE: When people walk, they're pedestrians. {bk11-l2b-f1-04.mp3}
 
-VOCAB: sign
 LINE: Signs show names, directions, and other information. {bk11-l2b-f1-05.mp3}
 
 VOCAB: signal
@@ -851,11 +849,9 @@ INTRO: Here are five signs every driver must know on sight. Look at each one, li
 INSTRUCTION: Repeat the words and sentences.
 REPEAT
 
-VOCAB: stop sign
 LINE: Stop at the stop sign and look both ways. Go when it's safe. {page_043_001.jpg} {bk11-l2b-f4-01.mp3}
 
 VOCAB: yield
-VOCAB: right-of-way
 LINE: Yield the right of way to the other driver. He can go ahead of you. {page_043_002.jpg} {bk11-l2b-f4-02.mp3}
 
 VOCAB: one-way
@@ -912,9 +908,6 @@ LINE: Because he knows that he'll have to learn how to drive downtown sometime,
 LINE: He looked at a city street map in advance, but that didn't help him when he got downtown. {st-page_046_001.jpg}
 LINE: The heavy traffic and all of the signs and signals there confused him. {st-page_046_001.jpg}
 
-VOCAB: one-way
-VOCAB: two-way
-VOCAB: intersection
 LINE: First, he drove the wrong way for two blocks on a one-way street. {st-page_046_002.jpg}
 LINE: He turned and got on a two-way street at the next intersection. {st-page_046_002.jpg}
 VOCAB: to flash
@@ -922,7 +915,6 @@ LINE: Then he saw that some red and blue lights were flashing off and on behind
 VOCAB: to pull over
 LINE: Finally he realized that an emergency vehicle was following him. He had to slow down and pull over to the side of the road while it passed. {st-page_046_002.jpg}
 
-VOCAB: railroad crossing
 VOCAB: way
 LINE: Then he came to a railroad crossing. The lights there were flashing, too. {st-page_046_003.jpg}
 LINE: He knew that signal meant that he had to stop because a train was coming. {st-page_046_003.jpg}