1.在示波器的荧光屏上发现水平方向有一亮斑自左向右移动,要使它在水平方向出现一条亮线的办法是( )
A.顺时针旋转灰度调节旋钮
B.调节衰减旋钮
C.调节扫描范围旋钮和扫描微调旋钮,增大扫描频率
D.调节Y增益旋钮
答案:C
64. A. apply B. reply C. respond D. direct
答案 50-54 AABBC 55-59DCDAB 60-64 CDABC
63. A. signs B. impacts C. results D. causes
62. A. emergency B. urgency C. tension D. stress
61. A. Pollution B. Exhaustion C. Breathing D. Heat
60. A. resist B. cure C. experience D. reduce
59. A. But B. Even C. Thus D. Or
58. A. harmful B. beneficial C. infectious D. useful
57. A. base B. standard C. space D. level
56. A. much safer B. hardly affected C. ill-protected D. barely attacked
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