预约成功
at a low/high speed 速度很慢/快地……
【例句】The signals go to and fro at a very high but almost constant speed. 那些信号用非常快但几乎不变的速度来回传送。
【拓展】speed 作名词的用法
(1)at + full/top/low/a high/an ordinary/the same + speed
以全(高、低、高、平常、同样)的速度
(2)"at a speed of... " 以……的速度
at a speed of 700 miles an hour
at a speed of 160m/s.
