см. тж. от времени до времени
• Today we see weather balloons on occasion , but passenger balloons are very rare.
• Every now and then , the blade may strike a bump, breaking loose fragments of ...
• The computer itself blunders ( every ) now and then .
• For 600,000 years rhyolitic lava erupted on the Yellowstone Plateau intermittently .
• At times ( or From time to time ), the basin water is shock treated.
• Evaporate to dryness, turning the granules occasionally to insure uniform coverage.