二、单项填空（本大题共15小题，每小题1分，共15分）
从下列每小题所给的A、B、C、D四个选项中，选出可以填入空白处的最佳选项
31. Gina was born _______Oct.1st ,1999. She is old enough to go to school.
A. to B. on C. at D. in
32. —Can you go swimming with us this afternoon?
—Sorry, I can’t. I_______ take care of my mother because she is ill.
A. can B. may C. would D. have to
