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 of bed, put on his dressing gown 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 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, so it is April Fool's Day. April Fool to you!" "Oh, it was the English boy next door!" Mr. Lee exclaimed   and almost smiled. He went back to bed and felt asleep at once. The bell did not ring again. From this passage, we learn that people can   _   on April Fool's Day.
say "Hello" to each other dance and sing at night play jokes on each other send presents to children