Barely had the bulldozers started when Museum of London archaeologists swooped.是什么意思？

Barely had the bulldozers started when Museum of London archaeologists swooped.

推土机刚一启动，伦敦博物馆的考古学家们就蜂拥而至了。

barely

adv. 仅仅，勉强，好容易才，几乎不，几乎没有，赤裸裸地，无遮蔽地，公然地，露骨地，公开地；

例句
They are regularly sent booklets about personal safety, but they barely read them as they have so much paperwork to deal with...
他们经常会收到关于人身安全问题的宣传册，但因为大量文案工作缠身，他们几乎无暇阅读。

had

v. 有（ have的过去式和过去分词 ），（亲属关系中）接受，拿，买到；

例句
He claimed that his parents had abandoned him...
他声称父母遗弃了他。

the

art. 指已提到的人（物），指说话人与听者已知的人（物），用于独一无二的事物前，与形容词最高级和序数词连用；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

bulldozers

n. 推土机( bulldozer的名词复数 )，恐吓者，威胁者；

例句
Barely had the bulldozers started when Museum of London archaeologists swooped.
推土机刚一启动，伦敦博物馆的考古学家们就蜂拥而至了。

started

v. 出发，启程( start的过去式和过去分词 )，起动，提出（问题），开办；

例句
He started eating an apple...
他开始吃苹果。

when

adv. 什么时候，（用于时间的表达方式之后）在那时，其时，当时；conj. 在…时，既然，如果；pron. 什么时候，那时；n. 时间，时候，日期，场合；

例句
It was a Christmas when shoppers passed by expensive silks in favor of more practical gifts.
这是一个购物者不理会昂贵的丝绸衣服而热衷于更实用礼物的圣诞节。

museum

n. 博物馆；

例句
Ari Hart recently received the accolade of being represented in the Museum of Modern Art.
阿里·哈特的作品最近有幸获选在现代艺术馆展出。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

London

n. 伦敦（英国首都）；

例句
Lord Salisbury bought the picture at auction in London some years ago...
几年前，索尔兹伯里勋爵在伦敦拍得了这幅画。

archaeologists

n. 考古学家( archaeologist的名词复数 )；

例句
Barely had the bulldozers started when Museum of London archaeologists swooped.
推土机刚一启动，伦敦博物馆的考古学家们就蜂拥而至了。

swooped

v. 俯冲，猛冲( swoop的过去式和过去分词 )；

例句
A seagull swooped down in front of her car, causing her to slam on the brakes.
一只海鸥突然扑到她的车前，她急忙猛踩刹车。