This document analyzes errors in two reaction papers written by L2 learners. It identifies common error categories and provides examples. The main categories are morphological agreement, tense, misuse, and punctuation. For each category, the document explains what it is, provides examples from the papers, and gives tips on how to avoid or correct typical mistakes in that area. These include ensuring subjects and verbs agree, maintaining consistent verb tense, checking word meanings in context and with a dictionary, and properly using punctuation.