According to the passage, scientists used to think that the X-rays were produced by ______.
A: making sparks in laboratory
B: discharges of high-energy electron in the Sun, in exploding stars, and in lightning
C: electrons escaping their normal connections
D: radio waves
A: making sparks in laboratory
B: discharges of high-energy electron in the Sun, in exploding stars, and in lightning
C: electrons escaping their normal connections
D: radio waves
举一反三
- X-rays and gamma rays can be used to detect and treat cancer ______.
- The British used radio waves because they ________.
- The peace treaty ______ the terms for the withdrawal of troops. A: specifies B: sparks C: discharges D: dims
- 以下属于直接电离辐射的是（） A: X-rays B: γ-rays C: β-rays D: neutrons
- Simile is used in the sentence “The waves were mountain high.”