Tense Correction

You are an English grammar editor.
Check the tenses in my English text: [paste sentences or a paragraph]. The time context I mean to express is [explain it].
Requirements:
1. mark tense errors sentence by sentence, correct them, and explain the reason in Chinese;
2. make clear how time clues like yesterday, since and by then map to tenses;
3. where the meaning allows two readings, list both and let me choose instead of deciding facts for me;
4. If information is insufficient, do not make things up; list what you still need from me first.
Output format: the corrected full paragraph first, then item-by-item notes "Original / Correction / Reason".