题目内容：

1        2          3

1.Sign I means __________.

A.people must wear protective glasses in this area B.people mustn't wear protective glasses in this area

C.it's dangerous to wear a pair of glasses in this area D.this pair of glasses is dangerous for people's eyes

2.Sign 2 is mainly for __________.

A.students B.teachers C.policemen D.drivers

3.Sign 3 is probably put up __________.

A.on the gate of a park B.on the gate of a school

C.on the wall of a reading room D.on the wall of a post office