第二章单元测试
  1. Cathode rays are deflected (偏转) in an electric field( )

  2. A:错 B:对
    答案:对
  3. STP usually refers to the temperature of 0℃ and the pressure of 101.325 kPa( )

  4. A:错 B:对
    答案:对
  5. Alkali metals are all first period elements( )

  6. A:对 B:错
    答案:错
  7. There are as many electrons outside the nucleus as there are units of positive charge on the nucleus. The atom as a whole is electrically neutral( )

  8. A:错 B:对
    答案:对
  9. X-rays are harmless to the human body( )

  10. A:对 B:错
    答案:错

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