Mark 9:28

And when he was come into the house, his disciples asked him privately, Why could not we cast him out?

When he had come into the house, his disciples asked him privately, "Why couldn't we cast it out?"

And when he was come into the house, his disciples asked him privately, `How is it' that we could not cast it out?

And he having come into the house, his disciples were questioning him by himself -- `Why were we not able to cast it forth?'

After Jesus had gone into the house, His disciples asked Him privately, “Why couldn’t we drive it out?”