41.   The radiation is X-rays and gamma rays, lethal to matter plunging into the black hole.

42.   The radiation was too strong for bystanders.

43.   The radiation was evidence of the penetrating power of the cosmic rays that constantly bombard Earth from space.

44.   The radiation was not as terrible as the chemotherapy that followed.

45.   They began to suspect that radiation might be a threat to health.

46.   Ultraviolet B, or UVB, radiation is the principal cause of sunburn.

47.   Ultraviolet radiation is most intense in the middle of a summer day when skies are clear.

48.   While less traumatic than surgery, radiation is time-consuming, requiring seven or eight weeks of five-times-a-week treatments.

49.   Radiation is a risk factor for leukemia, but tests for radioactive substances in the area proved negative.

50.   Radiation is the energy given off by atoms.