The Power boiled in her till she thought she must burst; her knees quivered with the effort of standing.

Her knees were quivering.

That surprised him, but didn't make his knees quiver as it might once have done.

Maybe he didn't recognize the sounds of five terrified kids whose knees were quivering and teeth were chattering.

Her knees quivered at the pleasure, and she sighed with the longing building up inside her.

Her knees quivered as she sought to maintain the crouch.

His calves and thighs were painfully tender, and his knees and ankles quivered with each step.

Opaka felt her knees quiver.

He felt rag-limp, and his knees were quivering, and his stomach was twisting and rolling.

His knees quivered with his relief when he saw that Sarah was alive and unhurt.