動詞 flag down:

1. signal to stop

1. A policeman flagged down the car with his flash light.
   警察揮動閃光燈讓那輛車停下。
2. Our car ran out of petrol on the moors but fortunately we were able to flag down a passing motorist who took up to the nearest garage.
   我們的汽車在荒野里沒有汽油了，不過幸運的是，我們揮手請一位經過的開車者停下，把我們拉最遑的汽車車修理廠去了。