Relative Clause

In the sentence below:

Exercises, which were corrected by the teacher on the blackboard, made a lot of mistakes.

and it can be rewritten:

Exercises,corrected by the teacher on the blackboard,made a lot of mistate.

However,I read in a book, I see they write:

Exercises,to be corrected by the teacher on the blackboard,made a lot of mistake.

Could you tell me differences between 1(2) sentence(s) above and the last sentence.

Thanks!

[RonBee]

Commentary.

Exercises, which were corrected by the teacher on the blackboard, made a lot of mistakes.

That should read: "The exercises, which were corrected by the teacher on the blackboard, contained a lot of mistakes." (Excercises can't make mistakes.)

Exercises,corrected by the teacher on the blackboard,made a lot of mistate.

Mistake (not mistate) needs to be plural to conform with "a lot of".

Exercises,to be corrected by the teacher on the blackboard,made a lot of mistake.

You need to rewrite that. It should be: "The excercises, which were to be corrected by the teacher at the blackbooard, contained a lot of mistakes."

8)

[Tdol]

Or:
"The excercises, to be corrected by the teacher at the blackbooard, contained a lot of mistakes."