高千伏摄影的管电压应高于()
A.60kV
B.80kV
C.100kV
D.120kV
E.160kV
参考答案:D
解析:高千伏摄影的管电压应是120kV以上。
—When did he leave the classroom?
—He left _____you turned back to write on the blackboard.
A.the minute
B.the time
C.until
D.before
磷酸盐铁垢的成分、特征及生成部位如何?