【正文】 put up a tent yesterday. He often goes camping. I went swimming yesterday. I go swimming every day. She jogged last Sunday. She skated last weekend. She likes jogging. She likes skating. She sings happily. She sang happily. I am at school. I was at school. She listens to the radio. She listened to the radio. There are some boys on the playground. There were some boys on the playground. More examples: My father and I went fishing yesterday. My father and I go boating yesterday. didn’t The students were in the classroom. The students were not on the playground. We watched a film. We didn’t watch a film. The students visited the Palace Museum. The students didn’t visit the Palace Museum. They were in the classroom. They weren’t in the classroom. There was a pencil in the bag. There wasn’t a pencil in the bag. They played basketball. They didn’t play football. Did they play basketball? Yes, they did. Did they play football? No, they didn’t. There was a bird in the tree. Was there a bird in the tree? Yes, there was. No, there wasn’t. Alice sat by a river with her sister. Alice didn’t sit by a river with her sister. Did Alice sit by a river with her sister? Yes, she did. No, she didn’t. More examples: She found herself alone in a long, low hall. She didn’t find herself alone in a long, low hall. Did she find herself alone in a long, low hall? Yes, she did. No, she didn’t. She could see a lovely gard