What should a girl do who wishes to wear the hijab while studying medicine in a secular country, but fears failing because of it? And is it permissible for her to delay wearing it until after graduation?

A woman must wear the hijab in front of non-mahram men, based on the Almighty's saying: (O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks all over their bodies. That will be better, that they should be known so as not to be annoyed. And Allah is Ever Oft-Forgiving, Most Merciful) Al-Ahzab / 59, and the Almighty's saying: (And tell the believing women to lower their gaze and protect their private parts and not to show off their adornment except only that which is apparent) An-Nur / 31. It is not permissible to remove the hijab under the pretext of studying. A girl must adhere to her religion and remain committed to her hijab, even if it leads to abandoning her studies. Whoever trusts in Allah, He will suffice him and protect him and facilitate his affairs. Allah the Almighty said: (And whosoever fears Allah and keeps his duty to Him, He will make a way for him to get out (from every difficulty). And He will provide him from where he does not expect. And whosoever puts his trust in Allah, then He will suffice him. Indeed, Allah will accomplish His purpose. Verily, for all things has Allah appointed a due proportion) At-Talaq / 2, 3. She must be patient with harm and ridicule, while keeping in mind the great reward for those who adhere to their religion, as the Prophet (peace be upon him) said: "Indeed, behind you are days of patience, the one who adheres to it will have the reward of fifty martyrs among you."