这把剪刀太钝了，需要磨一下。

These scissors are too dull; they need to be ___sharpened.

练习写作可以磨炼你的表达能力。

Practicing writing can ___sharpen your expressive skills.

随着眼镜调整到位，远处的标志变得清晰起来。

The distant sign ___came into focus as my glasses were adjusted properly.

柠檬的酸味让这道菜的鲜味更加突出。

The lemon's acidity ___sharpened the dish's umami flavor.