سوال ۳ کنکور ارشد علوم کامپیوتر ۱۴۰۵

The blank needs a transitive verb that can take a that-clause and means "came to find out / realize." Only discovered fits: She soon discovered that the local people had no interest in her stories.

Why the others fail:

• happened — takes that only in the impersonal frame It happened that..., not with a personal subject (She happened to... needs an infinitive).
• developed — means "grew/created"; it does not introduce a that-clause of realization.
• existed — intransitive ("to be present"); it cannot take a that-clause object.

Exam trick: Match the verb to the grammar that follows it. A blank immediately followed by a that-clause of information favors a cognition/perception verb such as discover, realize, notice, find.