如下图所示，电流I等于（）。
A．0.2A
B．0.4A
C．-0.2A
D．-0.4A
参考答案：A
Outline: 1. General situation of crime victims in U. S.
2. The most frequent victims of crimes and their implications.
3. Your comments.
WITH TYPE OF CRIME
四冲程柴油机的气阀重叠角是指：（）.
A.上止点前后
B.下止点前后
C.上止点前
D.排气结束后
