keep up

动词 keep up:

1. maintain a required pace or level
2. lengthen or extend in duration or space
   同义词：prolong, sustain
3. keep in safety and protect from harm, decay, loss, or destruction
   同义词：conserve, preserve, maintain
4. keep informed
   同义词：keep abreast, follow
5. prevent from going to bed at night

1. The house is becoming too expensive for them to keep up.
   他们的房子维修费用贵得越来越修不起了。
2. The high cost of raw materials is keeping prices up.
   原料费用昂贵使得产品价格居高不下。
3. The enemy kept up their bombardment day and night.
   敌军一直日夜不停地狂轰滥炸。