In this task, you're given a sentence and your task is to generate a simplified sentence that focuses on lexical paraphrasing from the original sentence given in the input.

design philosophies two basic designs exist : event-driven -lrb- priority scheduling -rrb- designs switch tasks only when an event of higher priority needs service , called pre-emptive priority.
pre-emptive priority is when regular work is done until a higher priority job comes in.

a historian has stated that " it was quinine 's efficacy that gave colonists fresh opportunities to swarm into the gold coast , nigeria and other parts of west africa ".
a historian said , " it was quinine 's efficacy that gave colonists fresh opportunities to swarm into the gold coast , nigeria , and other parts of west africa ..

the winter solstice occurs at the instant when the sun 's position in the sky is at its greatest angular distance on the other side of the equatorial plane from the observer 's hemisphere.

the winter solstice occurs at the instant when the sun 's position in the sky is at its greatest distance on the other side of the equatorial plane from the observer 's hemisphere.