She ............ have to buy a new dress because her mother bought her one.
)don't -doesn't -didn't -needn't

the right answer is " doesn't" because of the sequence of the tenses here. If the sentence was
she ..........have to buy a dress because her mother had bought her one. the right answer would be : didn't>
Mr. Amer Abd- Elrahman
01140463162

didn't

This is past simple. So, if we add "ten years ago" to the sentence, for example, it will be more obvious.
So, the present simple here wouldn't be suitable. Instead, the present perfect would be more suitable after .because" just to choose "doesn't"

الإجابة الصحيحة
didn't

عشان هتنفع doesn't محتاجين مضارع تام بعد because عشان شراء الفستان هيكون له أثر فى الحاضر بدليل إن البنت لن تشتر الفستان

didn’t
اتمنى تكون صح

the right answer is did not