Puzzle Time: In/Out - True of Rat, Not of Mouse

[diebitter]

I'm 'in'. The rest of you are 'out'.

As an 'in' I say statements of truth. You cannot guess directly at what this truth is, you must make statements like mine, and I tell you whether they are my truth or not. NOTE: MY truth is consistent and will not change through the challenge.

IF you get enough 'truths' to convince me you know my 'truth' - usually 3 statements in a row that are correct - you become 'in', and have the same powers as me - but all 'in' people stick to the same truth, as set by me.

You need to look for patterns in this so when I say 'X is true, but Y is false' you need to work out what rule or pattern is true for X (and all following statements), but not true for Y

Example #1:
It's true for yesterday but not for last week
It's true for submarine but not for submersible
It's true for revolution but not for revolt
Answer in white: <font color="white"> They are words from the titles of tracks by the Beatles </font>

Example #2:
It's true for book but not for literature
It's true for seen but not for visible
It's true for bookkeeper 3 times over, but not for librarian
Answer in white: <font color="white"> The word contains a two consecutive same letters</font>


So, the answer can be about word patterns, or from 'lists' from the outside word, or in fact any reasonable construct/pattern involving words and letters.

PLEASE DO NOT EVER SAY OUTRIGHT WHAT YOU THINK THE PATTERN IS.

Okay, this first one from me reasonably simple is:

It's true for rat but not for mouse
It's true for pot but not for kettle
It's true for trap but not for ambush


(Now, if you have an idea what it is, please say it in the form 'It's true for A, but not for B'. I will confirm if it's correct or not.)