Here's why:
* "Now" indicates the present moment. It's used to describe something happening at the current time.
* The past simple refers to actions or events that happened in the past.
Example:
* Incorrect: "Now I went to the store." (This implies you're going to the store right now)
* Correct: "I went to the store yesterday."
However, there are a few exceptions where "now" can be used in conjunction with the past simple, but in these cases, "now" is not referring to the present time:
* To describe a past action that is still ongoing or has a lasting impact: "Now I understand why she said that."
* In fictional narratives, "now" can be used to describe a past event in the story: "Now, the hero faced his greatest challenge."
In most cases, it's best to use specific time words or phrases to indicate the past, such as:
* yesterday
* last week
* a few days ago
* in 2022
* when I was a child
Let me know if you have any other questions!