X线机对接地电阻的要求是
A.小于8Ω
B.小于71Ω
C.小于6Ω
D.小于5Ω
E.小于4Ω
参考答案:E
解析:X线机接地装置由接地极和连结导线组成,总接地电阻要求小于412。
心悸伴发热见于下列疾病,除外 ()
A.心肌炎
B.心绞痛
C.急性传染病
D.心包炎
E.风湿热
Thousands of athletes _______ in many countries competed ________ medals in the 2008 Olympic
Games in Beijing. [ ]
A. will involve ; in
B. involving; by
C. involved; against
D. involved; for