Mr . Lee was in bed and was trying to go to sleep when he heard the bell ring . He turned on the light and looked at his clock . It was twelve o'clock . "Who can it be at this time of night?" He thought . He decided to go and find out . So he got up , put on his dressing gown( 浴袍 ) and went to the door . When he opened the door , there was nobody there . "That is very strange . " Then he went back to his bedroom , took off his dressing gown , got back into bed , turned off the light and tried to go to sleep . A few minutes later he heard the bell ring again . Mr . Lee jumped out of bed very quickly and rushed to the door . He opened it , but again he found no one there . He closed the door and tried not to feel angry . Then he saw a piece of paper on the floor . He picked it up . There were some words on it : "It is now after midnight( 午夜 ) , so it is April Fool's Day( 愚人节 ) . April fool to you!" "Oh , it was the English boy next door!" Mr . Lee exclaimed( 惊叫 ) and almost smiled . He went back to bed and felt asleep at once . The bell did not ring again .