Sentence:  In their suburban cottage the crown charges , the Krogers <WSD>received</WSD> secrets from the mystery man , usually on the first Saturday evening of each month , and spent much of the week-end getting the secrets off to Moscow , either on a powerful transmitter buried under the kitchen floor or as dots posted over period marks in used books . 
Meaning of the word marked with <WSD> tags:  register (perceptual input)