关于这个问题，改变句子中的动词前面加上否定词not或者把否定词放在动词之前。例如：

肯定句：I am happy.

否定句：I am not happy. 或者 I am unhappy.

肯定句：She goes to school every day.

否定句：She does not go to school every day. 或者 She doesn't go to school every day.