They had accidentally damaged a gas pipe while drilling...是什么意思？

They had accidentally damaged a gas pipe while drilling...

打钻时，他们不小心钻破了一根燃气管道。

they

pron. 他/她/它们，人们，大家，政府，当局，她们；

例句
The storms had abated by the time they rounded Cape Horn.
他们绕过合恩角时，暴风雨已经减弱。

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。

accidentally

adv. 偶然地，意外地，非故意地；

例句
He accidentally electrocuted himself.
他意外触电身亡。

damaged

adj. 被损坏的；v. 损害，毁坏，加害于( damage的过去式和过去分词 )；

例句
The bomb destroyed a police station and badly damaged a church...
炸弹摧毁了一处警察局，并使一座教堂严重受损。

gas

n. 气体，[矿业] 瓦斯，汽油，毒气；vt. 加油，毒（死）；vi. 加油，放出气体，空谈；int. 该死！（令人气愤的人应即被送毒气室处死）；

例句
Methane is often regarded as the second most important greenhouse gas after carbon dioxide.
甲烷常被认为是仅次于二氧化碳的重要温室气体。

pipe

n. 管子，烟斗，管乐器，（管风琴的）音管；vt. 以管输送，用管乐器演奏，尖声唱；vi. 吹奏管乐器，尖叫，尖声地说（或唱），尖声啼鸣，[航海] 吹长哨；

例句
He smacked the bowl of his pipe into his hand.
他在自己手上磕打烟斗。

while

conj. 在…期间，与…同时，虽然，

例句
A Dr Matthew Owens was reported missing while on an expedition to north-eastern Turkey.
据报道，一位叫马修·欧文斯的博士在前往土耳其东北部考察的途中失踪了。

drilling

n. 演练；v. 钻（孔）( drill的现在分词 )，打（眼），操练，训练；

例句
The decision to allow more offshore oil drilling angered some Californians.
允许进行更多近海石油钻探的决定激怒了一些加利福尼亚人。