不能透过血脑屏障的药物是（）A、第3代头孢菌素 B、磺胺嘧啶 C、四环素 D、以上都

       We are in No.10 Middle School. We have many   1   in our school.
       We can't arrive late for school. We have to be in the   2   before the lesson begins. We can't eat food
  in class. If someone is   3  , he can eat food between two lessons. But we can't buy food   4   our
  school. We have to buy it in our school shop. And we can't   5   in class. We have to be quiet.
       In English classes, we have to do some   6  . Our English teacher says it is a good way to   7  
  English. Our Chinese teacher is a tall and heavy man. He is very strict with us. We have to   8   straight
  and listen to him carefully in class. Oh, we can't stand these rules,   9   nobody can break (违反) them.
       After class, we can't run in the hallways. It's  10  sometimes. Oh, we can't talk loudly in the dining
  hall as well.