Questions & Answers about היא הייתה כל כך מופתעת מהמתנה, שהיא לא אמרה כלום בהתחלה.
Because it uses the pronoun היא, which means she, and the other forms agree with it:
- הייתה = was in the feminine singular
- מופתעת = surprised in the feminine singular
- אמרה = said in the feminine singular
If the subject were masculine, you would expect forms like הוא, היה, מופתע, אמר.
Hebrew usually leaves out to be only in the present tense.
So:
- היא מופתעת = she is surprised
- היא הייתה מופתעת = she was surprised
In the past, Hebrew normally does use forms of היה / הייתה. So הייתה here is necessary to show that the situation was in the past.