题目

介词、冠词填空。1. ______ Monday we raise our national flag.2. We have _____ class meeting.3. We dance ______ the playground.4. We dance ______ Wednesday.5. What do you often do _____ Tuesday? 答案：【答案】1. On 2. a 3. in 4. on 5. on 【解析】略下列属于遗传病的一组是（　　） A、色盲和白化病B、缺铁性贫血C、肝炎和肺炎D、坏血病