New Revised Standard Version
When he had entered the house, his disciples asked him privately, “Why could we not cast it out?”

Contemporary English Version
After Jesus and the disciples had gone back home and were alone, they asked him, "Why couldn't we force out that demon?"

New American Bible
When he entered the house, his disciples asked him in private, “Why could we not drive it out?”

Douay-Rheims Bible
And when he was come into the house, his disciples secretly asked him: Why could not we cast him out?

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

asked.

Mark 4:10,34 And when he was alone, the twelve that were with him asked him the parable. . . .

Matthew 13:10,36 And his disciples came and said to him: Why speakest thou to them in parables? . . .

Matthew 15:15 And Peter answering, said to him: Expound to us this parable.

Why.

Matthew 17:19,20 Jesus said to them: Because of your unbelief. For, amen I say to you, if you have faith as a grain of mustard seed, you shall say to this mountain: Remove from hence hither, and it shall remove: and nothing shall be impossible to you. . . .