数字数据网DDN是一种基于( )连接的窄带公共数据网。
参考答案:点—点
阅读对话,并回答下列问题。
John: Hi, Sarah. What are you going to do?
Sarah: I'm going to the cinema. How about you?
John: I'm going to the bookstore. What film are you going to see?
Sarah: Harry Porter.
John: Really? It's a nice film. I hope you'll have a good time.
Sarah: Thank you. How can you get to the bookstore? By taxi?
John: No. I think it is too expensive. I'm going there by bike. Because it's good exercise.
Sarah: OK. I have to go now. Goodbye.
John: Bye.
1. Who is going to the cinema?
2. What is John going to do?
3. Are they going to the pet shop?
4. What's the name of the film?
上颌切牙开髓时,应由舌面窝向颈部方位钻入的原因是()
A.近一远中径近切嵴处髓腔最宽
B.横切面髓腔呈圆三角形
C.横切面髓腔唇侧比舌侧宽
D.在牙颈部附近髓腔唇-舌径最大
E.根管粗、直、根尖孔大