it v-link ADJ wh
The 'clear' group
These adjectives indicate that something is certain, uncertain, or obvious. Most of these adjectives are used with a range of finite wh-clauses.
It's not certain whether his outfit, goggles or bike are authentic antique articles.
It was not clear what had caused the bus to crash through the bridge railings, Sgt Monk said.
It should be obvious why motorists must stop and give way to pedestrians on a crossing.
Debatable, doubtful, and questionable are typically followed by a clause beginning with how, if, or whether.
With the night life running until dawn, it's debatable how much rest you'll get during your stay.
Indeed, he said, it was doubtful if the bank had ever been profitable since its establishment in 1972.
Arguable, dubious, and undecided are typically followed by a clause beginning with whether.
It is extremely dubious whether these employees will ever be given any rights at all.
Understandable is typically followed by a clause beginning with why or how.
It's understandable there's such an appetite for change throughout the city.
Clear, obvious, and unclear are occasionally followed by a wh-to-inf clause. This pattern is it v-link ADJ wh-to-inf.
apparent arguable certain clear debatable doubtful dubious evident obvious plain questionable uncertain unclear undecided understandable unknown
It is not clear how to reconcile these results.
In the case of clear, debatable, doubtful, and unclear, there is sometimes the preposition as to between the adjective and the wh-clause. This pattern is it v-link ADJ as to wh.
It was not clear as to where the two victims were shot.