______对边平行的四边形叫梯形,______对边分别平行的四边形叫平行四边形.
只有一组对边平行的四边形叫梯形,两组对边分别平行的四边形叫平行四边形;
故答案为:只有一组,两组.
1. 根据所读内容将Helen, Jane, Gina 三个名字分别填入相应的横线上
①___________ ②_____________③_____________
2. The three girls wrote to ask for ________________________.
3. The underlined words “turned her back on me” means “________________________” in Chinese
4. It is clear that Helen is not ________________________ with her parents.
5. According to the advice, Jane should ________________________ her friend as usual.
()是气象事业的基础,对地球系统各个圈层的观测具有长期、不间断、立体、综合、大规模的特征,内容涉及大气物理、大气化学及描述地球环境的诸多参数。