I caught him a lap later, and although I could pass him I could not shake him off...是什么意思？

I caught him a lap later, and although I could pass him I could not shake him off...

一圈后我追上了他，可是虽然我可以超过他，但却甩不掉他。

caught

v. 赶上( catch的过去式和过去分词 )，接住，引起，看见；

例句
The men were caught in the act of digging up buried explosives.
那些人在挖掘掩埋的爆炸物时被逮个正着。

him

pron. (he的宾格)他；

例句
They said goodbye to him as he got aboard the train at Union Station.
当他在联合火车站登上火车之际，他们向他道别。

lap

vt. 折叠，包裹，缠绕，使搭接，磨亮，磨平；vi. 折叠，部分重叠，舔，包围；n. 膝，下摆，一圈跑道，范围；

例句
...that last lap of the race...
比赛最后一圈

later

adv. 较晚地，以后，过后，后来，随后；adj. 后来的，以后的，接近末期的，晚年的；

例句
Eleanor would later blame her mother-in-law for her husband's frequent absences.
埃莉诺过后会因丈夫经常不在家而责怪婆婆。

and

conj. 和，与，而且，于是，然后，因此；

例句
I spend a lot on expensive jewelry and clothing...
我花很多钱购买昂贵的首饰和衣服。

although

conj. 尽管，虽然，但是，然

例句
He was in love with her, although he did not put that name to it.
他爱着她，虽然他没有将其称为爱。

could

aux. “can”的过去式，能够，打算，用于假设语气的条件句，用于虚拟语气的结论句；

例句
The regulations were relaxed and the prisoners could get out and about a bit.
规定有所放宽，犯人可以出去短暂放风。

pass

vt.& vi. 走过，通过，批准，度过；vt. 传球，及格，发生，不要；n. 通道，通行证，关口，越过；

例句
Having read the book, she will be able to pass on the acquired knowledge to trainee teachers.
读完此书，她便能将从书中所得传授给实习教师。

not

adv. 不，[用以表示否定、否认、拒绝、禁止等]不是，几乎不，未必，没有[用于否定后面的词或短语]；

例句
It became very clear that the incident was not just an aberration, it was not just a single incident.
事实已经很清楚，这件事不是偶发的，它并不是一起孤立的事件。

shake

vt. 动摇，摇头，使发抖，使心绪不宁[烦恼，惊吓]；vi. 摇（出），抖（掉），握手，（嗓音）颤抖；n. 摇动，震动，哆嗦，混合饮料；

例句
...a man with more medals than you can shake a stick at.
拥有很多奖章的人

off

prep. 从…落下，离开，从…去掉，下班；adv. 离开，距，离，被取消，下班；adj. 不新鲜的，不能接受，不礼

例句
He eased his foot off the accelerator.
他松开了油门。