题目

若，则或的否命题是（ ）A.若，则或 B.若，则且C.若，则或 D.若，则且 答案：【答案】D【解析】将原命题的条件和结论都否定可得出其否命题，进而可得出结论.由题意可知，命题“若，则或”的否命题是“若，则且”.故选：D.阅读对话，选出正确的答案。My name is Tina. I like shopping very much, but I never go shopping on weekends. There are too many people in shop. I don’t like shopping with other people. It usually takes me much time to buy things because I never buy the first thing I see. I always look around other shops to find the same thing cheaper. I’m good at finding cheap things. I don’t like buying food in small shops or street markets. I think food in the supermarket is fresh and cheap.( )1. Does Tina like go shopping ?A. Yes, she does . B. No, she doesn’t . C. I don’t know.( )2. How does Tina go shopping on weekends ?A. Usually . B. Always . C.Never .( )3. Why does shopping take Tina much time ?A. Because there are too many people in shop .B. Because I never buy the first thing I see .C. Because I’m good at finding cheap things .( )4. Where does Tina buy food?A. In small shops .B. In street markets .C. In the supermarket.