Doubling the final consonant before a vowel

In English, when we add an ending that begins with a vowel (-ed, -ing, etc.) to a word that ends in a consonant, we sometimes double that consonant. But sometimes we don't! Do you know when to double? See if you can tell whether the words are correctly spelled in the questions below.

1. occurreda) correctb) incorrect
2. stooppeda) correctb) incorrect
3. acquittala) correctb) incorrect
4. benefiteda) correctb) incorrect
5. preferrencea) correctb) incorrect
6. gumya) correctb) incorrect
7. commitala) correctb) incorrect
8. indentinga) correctb) incorrect
9. fitteda) correctb) incorrect
10. maddena) correctb) incorrect