That has occurred only once before, last year.
By 4 °C global warming or earlier, almost all regions experience an intense heatwave yearly that occurred only once every 30 years between 1861 1890.
Mr. Ngom, sipping a Dewar's at the bar, said he enjoyed seeing his Senegalese friends, but was grateful that the concert occurred only once a year.
NOSVA occurred only once during 19 septic shock episodes and occurred two or more times during 11 septic shock episodes.
During a single step, avalanching occurred only once per cell (i.e., it was not repeated until perfect relaxation).
As far as we know, the Able Archer misperception occurred only once.
They told him that this type of weather effect occurred only once every hundred years.
Such a situation had occurred only once before in the previous three years.
This motif would be bad enough if it occurred only once, but Inarritu manages to employ it three times in the last 30 minutes of the film.
A further 13 strains belonged to novel STs and each occurred only once.
Twenty-three haploccurredccurred only once (Figure 3) while 15 haplotypes were observed in more than one malaria episode.
