21． What _______ pity that you must leave now! It is such _______ great fun to have dinner with you．
A． a; a B． a; the C． /; a D． a; /
22． Before joining the Department of Defense, Mr． Panetta _______ as director of the CIA from February 2009 to June 2011．
A． would serve B． served C． was served D． had been served
