knock

Which Means:

To hit with something heavy, or bang with your fist.

The runner knocked every hurdle down as he tried to jump over them.

Even though the K at the beginning of the word is silent, the C in the CK at the end is, too.

To crouch down on your knees.

I had to kneel down to reach under the desk.

Not only does this word have a silent K, its past tense can either be 'knelt' or 'kneeled.'