Aha! Your first mistake!

T H E / _ O _ E _ _ / O F / E _ _ O _ _

[X]

Letters left:

ABCDGIJKMNPQRSUVWXYZ

Easy now.

 

T H E / _ O _ E _ _ / O F / E R R O R _

[X]

Letters left:

ABCDGIJKMNPQSUVWXYZ

Wow! So I did. Let me see, what will we have....

How about another book!

_ _ _ _ _ _ _ _ _ _ _ _

Letters left: ABCDEFGHIJKLMNOPQRSTUVWXYZ

_ _ E _ _ _ _ _ _ _ _ _

Letters left: ABCDFGHIJKLMNOPQRSTUVWXYZ

Yep

_ _ E A _ _ _ _ _ _ _ _

Letters left: BCDFGHIJKLMNOPQRSTUVWXYZ

There be 2

_ _ E A _ O _ O _ _ _ _

Letters left: BCDFGHIJKLMNPQRSTUVWXYZ

Nope

_ _ E A _ O _ O _ _ _ _

Letters left: BCDFGHJKLMNPQRSTUVWXYZ
[X]

Don't be stupid

_ _ E A _ O _ O _ _ _ _

Letters left: BCDFGHJKLMNPQRSTVWXYZ
[X][X]

Nup

_ _ E A _ O _ O _ _ _ _

Letters left: BCDFGHJKLMNPQRSVWXYZ
[X][X][X]