All the way down to those which have only occurred twice.

And it's not the sort of opportunity that occurs twice.

In the last year we have had a questionable situation occur twice.

Such escape as we had a year ago could hardly be expected to occur twice.

Before that the highest number of students gaining 990 in one year, was four, which had occurred twice.

It's an event that occurs once or twice a year on average, but in recent years has been less frequent.

In severe cases, tumors may occur once or twice a month.

After the introduction of the yellow jersey in 1919, the situation occurred twice.

Actually, high tides occur twice a day, 12 hours and 25 minutes apart.

He said there are earthquakes that occur once or twice a year in their survey area.