My grandfather is a teacher. He is the head teacher of a school for boys between the ages of thirteen and eighteen. I know that he is a kind man, because he gives me presents , and let me sit on his knees , and tells me stories. But I believe  the boys at his school are afraid of him. At school, when he walks into a room full of boys, they will be quiet at once . When he looks at a boy with a certain look in his eyes, that boy's face goes red, and looks down at his shoes. If a boy brings careless work, my grandfather will pick up the boy's book and throw  it across the room, shouting , "Do it all again, and bring it back the first thing in the morning!" if the boy is late, or if he forgets to bring the work, he has to do it again, and again and yet again. My grandfather is   _  .
a kind teacher a teacher, and he gives presents to his students. the head teacher of a boy's school a boy at a school. In that school, everyone was afraid of the head teacher.