Those instruments exist in a class of their own.

It seems hard to believe that actual instruments that people actually played once existed.

The instruments he works on didn't exist five years ago.

No instrument for espionage this valuable had ever existed before.

Such an instrument now exists that is appropriate for the adolescent learner.

Neither these instruments nor these policies can exist by themselves; they are all linked together.

I added that the instruments do not exist at the moment but the problem cannot be avoided in future.

I said the instruments do not exist but the problem does.

Do such instruments exist and will they be effective?

Such instruments exist; now all we have to do is to use them.