動詞 keep up:

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

1. The house is becoming too expensive for them to keep up.
   他們的房子維修費(fèi)用貴得越來越修不起了。
2. The high cost of raw materials is keeping prices up.
   原料費(fèi)用昂貴使得產(chǎn)品價格居高不下。
3. The enemy kept up their bombardment day and night.
   敵軍一直日夜不停地狂轟濫炸。