1、riddlesWhatkindofdognevercanbiteandbark?Canyounamefivedaysofthe week without saying:Monday,Tuesday,Wednesday,Thursday,Friday?Howmanymonthshave28days?Whatisthecenterofgravity?Whoisn'tyoursisterandisn'tyourbrother,butisstill achildofyourmotherandfather?Lesson6Smashandgr