Sam is a good boy. He is tall and fat. He likes sports. In spring, he flies kites in the park. In summer, he plays football with his friends under the tree. In autumn, he goes fishing with his Dad in the lake. In winter, he plays snow with his pupils at school. He is happy each day.

在暑假中，张老师有事需要通知全班54名同学，采用的方案是把全班学生平均分成6个小组，老师分别通知6个组长，再由组长分别通知本组成员，如果每打一次电话至少要1分钟，所有同学接到通知时，至少需要（　　）分钟．

下列词语字形完全正确的一项是（    ）

按照要求写句子。

按肯定句改成双重否定句：

肯定句：那轻轻的潮声啊，是她睡熟的鼾声。

否定句：