keep up on的用法和樣例：
例句
- I was put to it to keep up with his pace.
我跟上他是不容易的。 - They had to bring the card index up to date.
他們使得索引卡片跟上發(fā)展，不致過(guò)時(shí)。 - I had to run to keep up with the girls.
我得跑以跟上女孩子們不落后。 - While research on plants has taken the lead, work with farm animals does not lag far behind.
盡管植物的研究工作領(lǐng)先一步，牲畜的研究工作也并不落后。
