doubtful
dubious *
dubitable
in question *

I had got to know the girl in question pretty well.

The building in question may not have been found yet.

The time period in question is quite a long one, from the 8th century to the 12th.

But the future of the project is now in question.

I kept a very close watch over the area in question.

Officials said they could not tell yet how much money was in question.

The kids in question were under the age of 4.

Sometimes the people in question could be said to know what they were talking about.

He had not even looked at the girl in question.

I would have given a great deal to find the person in question, and ask him.