Sequence classification

Hallo. I am working on my grduation project and it is my first project in ML
I am asked to highlight the sentence which their tag or label will be predicted. Now i have predicted. I have [id, tag, predictionstring]
Is there any way to highlight using the prediction string or i have to get the start and end chrachter for each predicted string.
Another question is : the Model predict just the long sentences for example concluding sentence and did not predict any closing or salutation. I dont know what is the wrong or how can i fix this. Thanks in advance