1 . Talented in both medicine and sports, Robin ________(tear) between becoming a doctor and an athlete when he graduated. (所给词的适当形式填空)

2 . The other day, we brought along pieces of old bread and__________(feed) the birds. (所给词的适当形式填空)

3 . He ________ (sharpen) his knife in order that he cut meat easily . （所给词的适当形式填空）