unanswerable

adj.

不能回答的；

1. For most of the students the question was unanswerable.
   对多数学生而言,这问题无法回答。
2. His case/defence is unanswerable.
   他的辩解无懈可击。

Unanswerable
Answerable and unanswerable questions
Time to register randomised trials: The case is now unanswerable
Time to register randomized trials. The case is now unanswerable
Helping children correctly say "I don't know"to unanswerable questions.
Questions of accountability: yes–no interrogatives that are unanswerable
In musculoskeletal epidemiology are we asking the unanswerable in questionnaires on physical load?
"Don't know"responding to answerable and unanswerable questions during misleading and hypnotic interviews.
The Effects of Accuracy Motivation on Children's and Adults' Event Recall, Suggestibility, and Their Answers to Unanswerable Questions
Does a Warning Help Children to More Accurately Remember an Event, to Resist Misleading Questions, and to Identify Unanswerable Ques...