问题
单项选择题 A1/A2型题
关于特征X线的叙述，正确的是（）
A.X线波长仅与管电压有关
B.内层轨道电子跃迁产生X线为特征放射
C.X射线谱是连续能量谱
D.电压升高特征放射能量增加
E.管电压升高特征射线的百分比减少
答案
参考答案：B
解析：靶原子的内层轨道电子被高速电子击脱，外壳层电子跃迁填充空位，多余的能量以光子的形式放出。形成特征X线。
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关于特征X线的叙述，正确的是（）
A.X线波长仅与管电压有关
B.内层轨道电子跃迁产生X线为特征放射
C.X射线谱是连续能量谱
D.电压升高特征放射能量增加
E.管电压升高特征射线的百分比减少
参考答案：B
解析：靶原子的内层轨道电子被高速电子击脱，外壳层电子跃迁填充空位，多余的能量以光子的形式放出。形成特征X线。
| 任务型阅读。 Here is a survey about people's preference (偏爱) to shop. Some people were asked where they preferred to shop. Eric is a doctor. He lives in a nice neighborhood with many small shops and restaurants. He likes the friendly shop owners. He doesn't have a car, so shopping near his home is very convenient (便利的). However, he says there are two main problems. First, things from the small shops cost more money. Second, he can't find the books he wants to read in the small bookstore. He has to go to the big bookstores downtown. Cathy is a mother of three children. She and her husband both work as teachers. They like to shop in big supermarkets because they're clean and safe and prices are good there. Supermarkets have many more kinds and sizes of products than small shops. Cathy says supermarkets also have disadvantages. For example, they're always crowded during holidays, and they're so big that children can easily get lost in them. Tony is a student who prefers to shop on the Internet. He thinks the main advantage is that he can shop anytime he likes, even late at night. And he can buy fascinating things from all over the world. The biggest worry is security (安全保障) for the Internet shop. Last year, his credit card number was stolen (窃取). Also, once he paid for some things and never received them. | ||||||||||||||||
| 根据短文内容，将下面表格中的信息补充完整。 | ||||||||||||||||
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