三、阅读短文，根据语篇要求填空，使短文通顺、意思完整。每空限填一词。
Biking is a popular way of traveling. Different countries have different rules for child riders.
In most countries, child riders must wear a helmet 1. biking. And some countries have 2. age limit（限制）for child riders. In China, children cannot ride on roads if they are 3. 12 years old.
In Germany（德国）, children must pass some exams 4. get a bike license（执照）before they ride on roads. It 5. cool but a little difficult, right?

1. when
2. an
3. under
4. to
5. is

四、补全对话。
(Mr. Zhang's neighbor, Xiao Ming, is knocking on the door. )
A: Excuse me, Mr. Zhang. Could you do me a favor?
B: Of course, Xiao Ming. 1. ?
A: My computer doesn't work. Can you help me fix it?
B: 2. . Let me have a look.
(After a while)
B: It's OK now.
A: Thank you, Mr. Zhang. It's very kind of you.
B: You're welcome. 3. ?
A: No, I'm not. I'm a little bored.
B: Would you like to play chess with me?
A: I'd love to, but I have to finish my homework first. 4. ?
B: Sure, no problem. You can come to my house after you finish it. See you later.
A: 5. . Thank you again.
B: That's all right.

1. What's wrong/What's the matter
2. Sure/Of course
3. Are you busy now
4. Can you wait for me
5. That's great