单词：keep up on
跟上
keep up on的用法和样例：
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.他们使得索引卡片跟上发展，不致过时。
- I had to run to keep up with the girls.我得跑以跟上女孩子们不落后。
- While research on plants has taken the lead, work with farm animals does not lag far behind.尽管植物的研究工作领先一步，牲畜的研究工作也并不落后。