Grammar quizzes have an English translation button for the complete sentence, so this translation includes the part(s) that are quizzed, which gives a considerable hint to the solution.
On the other hand, look-ups of individual words/expressions are impossible, though they would not include hints to the solution.
Therefore I‘d like to propose to allow word/expressions look-ups in the non-quizzed parts of the grammar quiz sentences, and maybe drop the translation of the complete sentences. But the latter is not that important.
The same is valid for sentence quizzes I assume, but I cannot check at the moment.
