Поставьте предложение в отрицательную форму: I was able to answer the question at once.
- I wasn't able answer the question at once.
- I wasn't able to answer the question at once.
- I wasn't to be able answer the question at once.
- I wasn't to be able to answer the question at once.
Для просмотра статистики ответов нужно
залогиниться.