Answer:
He must add evidence, citing scenes from the film where they prove his position against the plot.
Step-by-step explanation:
The author of the letter positions himself on his disgust about a particular film that was shown. He tells how the film has a poorly written plot, leaving the film pathetic and terrible, mainly due to the constant use of the words "you know" and "like". However, the author does not present any evidence that these elements exist in the film, in fact. This makes the text need some proof that the author could provide, citing some scenes that justify his dislike for the film shown.