根据短文内容，选择正确答案。
Jack is a teacher of English. He is not young, but he is not old. He has a round face and a big nose. He is
tall. There are fifty students in his class. They all like him. Now it's in the afternoon. Look, some students are
working in the classroom. Jack is there, too. He's helping them to study English. He is a good teacher, and he
is a good friend of them all.
1. What does Jack do?
A. He is a worker.
B. He's a teacher.
C. He's a doctor.
D. He's a nurse.
2. What does he look like?
A. He has a round face and a big nose and he is tall.
B. He is short and fat.
C. He has a small nose.
D. He has a long face.
3. How many students are there in his class?
A. There's fifteen students in his class.
B. There's fifty.
C. He has fifty.
D. There are fifty in it.
4. Jack is a good teacher, isn't he?
A. Yes, he isn't.
B. No, he is.
C. Yes, he's.
D. Yes, he is.
5. What are the students doing in the classroom?
A. They are working there.
B. They're doing their lessons.
C. They're helping their teacher.
D. They're good friends of Jack.
的药物与下列哪个药物的药理作用相似（）。