Work carefully so the bit doesn't penetrate the outside wall.

They opened fire, but their bullets couldn't penetrate the wall.

But penetrating the wall wasn't necessary for their main amusement.

Sometimes, an actor in a play may physically penetrate the fourth wall.

In the chamber everything looked much as it had before except that now a small hole penetrated the second wall.

Fear for his friend penetrated the blazing wall of agony.

If they should manage to penetrate the outer wall into the room we just left.

To reach that stream and carry out his plan to follow it, he would have to penetrate the wall of solid rock.

At this point, electron microscopy can no longer penetrate the wall.

Two weeks before the beginning of the game, a looped radio signal penetrated the wall.