现场总线分支电缆的长度应小于（）。
A、60m
B、90m
C、120m
D、1m
参考答案：C
Time ________ quickly. Three years passed before we knew it.
A．went by
B．went on
C．went away
D．went off
砌弧形拱时，拱座的坡度线要与胎模垂直。 ( )
