We have learned in the previous lessons that to form basic negative sentences, we can put "not" after the helping verb of a sentence. We can form negative present perfect sentences by simply putting "not" after the helping verb of the sentence (has/have).
We have highlighted the helping verb of each sentence with the color yellow and not (or contracted form n't) with the color red.
She has finished her homework.
1. They have visited the new museum.
2. She has completed her project.
3. I have finished my homework.
4. We have discussed the plan.
