He sliced and sliced, but the knife did not penetrate.

The knife should never penetrate deeply enough to slice the clam meat.

Guided by a skilled hand, the knife had penetrated his heart, bringing instant, silent death.

The knife penetrated the pericardium and cut the surface of the heart.

Was that why knives and bullets didn't penetrate their uniforms?

It apparently held gas, and under considerable pressure, for a faint hiss could be heard as the knife penetrated.

The police said the knife penetrated the officer's uniform and a bulletproof vest.

The knife penetrated the man's heart and he died moments later having staggered back to fall on the pavement outside his own house.

Place the potatoes in the oven and bake for 35 to 40 minutes until a knife penetrates them easily.

The skin was surprisingly tough and springy; the knife dented it, but didn't penetrate.