进入ETC车道的车速多少合适，安全车距为多少？
参考答案：限速20km/h，两车保持20米以上距离。
I think I was at school, ______I was staying with a friend during the vacation when I heard the news.
A．even so
B．and then
C．so that
D．or else
如何确定汽轮机试验运行工况及系统隔离？
