1.If you get something bad on the Internet, tell your _______.

A little sister

B little brother

C doctor

D parents or teachers

解析：选D。细节理解题。从Do的第二条When you get something bad on the Internet, tell your parents or teachers.可知，如果在网上看到不良信息，应该告诉父母或老师，故选D。

2.There are _______ Internet safety tips.

A three

B four

C five

D eight

解析：选D。细节理解题。网络安全使用提示有三条我们能做的和五条我们不能做的，总共8条，故选D。

3.You can’t _______ when you are on the Internet.

A tell your home address

B read news

C know everyone

D talk about teachers

解析：选A。细节理解题。从Do not中可知，我们不能告诉网上陌生人我们的家庭住址等重要的个人信息，故选A。

4.The passage tells us how to ______.

A play computer games

B use the Internet safely

C play with parents

D talk about teachers

解析：选B。主旨大意题。根据标题Internet Safety Tips可知，本文关于如何安全地使用网络，故选B。

5.The passage is mainly for _______.

A little kids

B police

C teachers

D boys

解析：选A。推理判断题。从Do和Do not中可知，这些提示主要是针对小孩提出的，比如不告诉陌生人自己的姓名、电话等信息；如果看到不良信息，告诉自己的父母或老师等，故选A。