at Easter

应该是用AT吧

at Easter

at Easter or on Eastetr Day

on Easter          来自网站------Today, baskets are used for the Easter Bunny to hide colored eggs and other goodies in for children to find on Easter!
     另一网站 ----- On Easter, many people go to church to celebrate Jesus’ resurrection(n.复活) from the dead. The Bible tells about Jesus and His death and resurrection. Jesus died because of people’s sins(n.罪). But He rose again and gave forgiveness and new life to everyone who believes in Him. Isn’t that something to celebrate in spring?