问题补充:
Can 16-year-old students drive to school?
No, they shouldn’t to drive because they aren’t serious enough.
A. allow
B. be allowed
C. allowed
D. have allowed
答案:
A. allow
(答案→)B. be allowed
C. allowed
D. have allowed
解析:从上下文可知,他们是被许可的对象,所以用被动语态,选B。