Regular repeating actions such as sound waves, light waves, or radio waves have a certain frequency, or number of waves per second.
有规律的重复活动如声波、光波、无线电波都有一个特定的频率，或者说是每秒的波动次数。
《柯林斯英汉双解大词典》
2
Another belief involving the number three has it that it is unlucky to light three cigarettes from the one match.
另一种与数字3有关的信仰认为，用一根火柴点燃三根香烟是不吉利的。
3
In Switzerland, if you were simply to anticipate a traffic light, the chances are that the motorist behind you would take your number and report you to the police.