Tanaka:
例文の選定がまずかったです。 
The choice of example sentence wasn't wise.
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See also GG5.
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I'm not sure that "model sentence" is quite right, actually.
Isn't that more like a sentence that you use as a model, rather than a sentence that illustrates the use of a word or grammatical construction?
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E.g.
MODEL SENTENCE: The gallows stood in a small yard, separate from the main grounds of the prison, and overgrown with tall prickly weeds.--George Orwell, "A Hanging"

(Write a sentence according to the pattern of the model sentence.)

IMITATION: The dog shivered in the background, wet from nosing his way through the early-morning grasses and covered with damp cocklespurs.
Source:
http://grammar.about.com/od/rs/g/Sentence-Imitation.htm

@@ -17,0 +18,2 @@
+<gloss>example sentence</gloss>
+<gloss>illustrative sentence</gloss>