Final answer:
The idiom 'A card up my sleeve' means to have a hidden advantage or plan. 'A bitter pill to swallow' means to accept something difficult. 'Out in left field' means to be uninformed about something.
Step-by-step explanation:
The idiom in sentence 1, 'A card up my sleeve', means to have a hidden advantage or plan that others are not aware of. It suggests that the person still has one more idea or resource to use.
The idiom in sentence 2, 'A bitter pill to swallow', means to accept or deal with something unpleasant or difficult. In this context, it refers to the student having to accept being grounded by their parents.
The idiom in sentence 3, 'Out in left field', means to be unaware or uninformed about something. In this context, it suggests that the student felt lost or unprepared in class because they had not read the required chapter.
Learn more about Idioms in English