他做饭前总是磨刀，以确保它们锋利有效。

He always ___sharpens his knives before cooking to ensure they are effective.

为了书写整洁，你需要定期削尖铅笔。

To write neatly, you need to ___sharpen the pencil regularly.

艺术家磨尖了炭笔，以便在素描中创作精细的细节。

The artist ___sharpened the charcoal stick to create fine details in the sketch.