1.She has already lived here for ten years.
问题描述：
1.She has already lived here for ten years.
2.You had better go with us.
改成否定句
答
She has not lived here for ten years.
You had better not go with us.
这两句的否定都是加not,没有什么原因
只是英语里的固定用法
这一类的用法
还是要多多积累