感应同步器主要技术参数有动态范围、精度、分辨率,其中动态范围为()。
A、0.2~40m
B、0.2~20m
C、0.3~40m
D、0.3~20m
参考答案:A
9. The other day he ran across one of his friends on the street, whom he ___________for ages.
A.hadn’t seen
B.didn’t see
C.hasn’t seen
D.doesn’t see
地球的物种每过3000万年左右,就会发生一次大的灭绝事件