下列选项中,不属于离心泵流量调节方法的是()。
A、节流调节
B、固定调节
C、旁路返回调节
D、变速调节
参考答案:B
Everyone present at the party was given a nice little gift with a suitable poem ________ to it.
A.attacked
B.attracted
C.attached
D.attributed
地铁通道内空气对流强,发生火灾时火势蔓延速度快。()