短文改错 One day,Mr.Li was reading his book in the teacher's off

One day,Mr.Li was reading his book in the【teacher's--teachers'】office while a football broke through the window and hit him on【加上the】 back of his head.Mr.Li was 【great--greatly】 shocked and felt angry.He took the ball and went 【去掉to】 downstairs to see who on earth threw the ball.He met a little boy at the doorway 【but--and】 the boy said it was 【him--he】 who had thrown the ball.The boy 【express--expressed】 his deep sorrow to Mr.Li,promising that he 【will--would】 take enough care afterwards.Mr.Li praised the boy for his 【honest--honesty】.The boy thanked him【 of--for】 his kindness and said good-bye to him,running away with the ball.