Which sentences use a standard modal-perfect construction? Select all that apply.
We should have checked the weather.✓Правильный ответ
They could have taken the earlier train.✓Правильный ответ
She should of backed up the folder.
He could of asked for directions.
Объяснение
The correct sentences place have after the modals should and could and before a past participle. The versions with of substitute a preposition for the auxiliary, so they cannot form the required verb phrase.