SUPER LATE on this one sorry about that. It would've made more sense to people had you included the paragraph that is part of the lesson, but since I have this question as well, I will write my answer down for you.
Answer:
I noticed that multiple periods where being used in a row, multiple times. I also noticed that a colon (:) was used to abbreviate the word "January". There was a specific instance where a semi colon was placed after three periods.
Hope this helps.