[jiǎn sù]
moderate; reduce the speed; shift down; speed reduction; delay; slow-up; slow down; decelerate; retard
be slow down to twenty miles an hour
減速至每小時20英里
The road is slippery; you'd better slow down.
路很滑， 你最好減速。
The motorcar slowed up over the bridge.
汽車減速過橋。