If your grammar book gave these as absolute rules, it is not a very good book. You know that English is full of exceptions, and the book should have made a point of this.
The "ible" ending for adjectives is from the word "able", and is generally used to describe the passive ability/possibility of the noun.
edible (from eat) means "able to be eaten".
approachable - able to be approached.
This is why I hate that advertisers use "breathable" to describe cotton clothes or, even worse, certain feminine hygiene products. These are definitley not able to be breathed!
So, anyway, "attractible" would be "able to be attracted", not "able to attract", which is why the form is "attractive" - "able to attract".
When you teach this lesson, add the word "usually" to the book �s rules, and warn the students that English doesn �t strictly follow its rules.
Bruce
