keep in抑制； 闭门不出； 让火不熄keepv.保持；保留；继续；贮藏；经营；遵守；供给；照管；饲养；耽搁；保持食物不变质；健康状况如何；保守（秘密@）；记录；遵守；保护n.生计；保存；城堡主楼；监狱；围墙Keep the fire in.让火一直烧着吧。Keep-alive effect保活效果keep to the subjectadj.把握主题keep at arms lengthadj.避免同某人亲近(敬而远之)keep one's thumb onkeep out of the wayvi.避开keep-fit exercise健身操keep one's nose outKeep one's anger inKeep down the weeds不让野草生长

1. I was put to it to keep up with his pace.
   我跟上他是不容易的。
2. 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。
3. I had to run to keep up with the girls.
   我得跑以跟上女孩子们不落后。
4. 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。