Sentence:  Peter, after the manner of man at the breakfast table, had allowed half his kedgeree to get cold and was sniggering over a letter. Sophia looked at him <WSD>sharply</WSD>. The only letter she had received was from her mother. Sophia's mother was not a humourist. 
Meaning of the word marked with <WSD> tags:  In an intellectually alert and penetrating manner.