You are to keep your knees wide at all times.

She needs to keep her knees together for a year and see if she can write anything positive.

It was hard to keep his knees straight as he started forward.

I dug fingers into his back to keep my suddenly weak knees from giving out.

Let him think whatever he wanted if it kept his knees knocking.

It was all she could do to keep her knees straight.

She concentrated on keeping her knees from knocking together all the way down.

He needed such ideas right now to keep his knees from trembling.

"And then something was scratching on the door," I added, trying to keep my knees from shaking.

It was only with an effort that he kept his knees from buckling.