The [verbable](#/lesson/Verbs.Ot09) is not a _verb_ but an _adjective._
Thus, the verb preceding the verbable _is not an auxiliary verb!_ It is, in fact, a [link verb](#/lesson/WordOrder.32).
The verbable is usually preceded by the [link verbs](#/lesson/WordOrder.32) _blijven, vallen_ or _zijn_ (these are all [irregular verbs](#/lesson/Verbs.Ir01)).
blijven | to stay | het blijft te proberen | it remains possible to try
vallen | to fall | het valt te proberen | it is possible to try
zijn | to be | het was te proberen geweest | it had been possible to try
The statement that we are not dealing with an auxiliary verb here must be rather confusing as the construction clearly consists of 'te' and a _verb_. The last example shows us that _zijn_ (in the pluperfect: _was geweest)_ is not an auxiliary verb. Had it been an auxiliary verb for _proberen,_ the past participle would have [turned into an infinitive](#/lesson/Verbs.Au05).