Question

英语语法问题

新概念英语第二册 90 课 What's for supper? 中 Oil rigs have to be repaired frequently and divers, who often have to work in darkness a hundred feet under water, have been frightened out of their wits by giant fish bumping into them as they work. 一句中 as they work 怎么理解？为什么不用 as they worked？
是不是
...by giant fish which bump into them as they work. 而不是 ...by giant fish which bumped into them as they worked.
实在搞不清楚了。拜托各位高手了，只能15分了，我现在只有40分，还想提问。

Answer 1

as they work 中的 they 指代Oil rigs ，该句的时态是一般现在时，应为从第一句Oil rigs have to... 就能看出用的时have ,所以要用work

Answer 2

应为前面是have，时态要保持一致，frightened 是过去分词，不是表过去时态，所以用work,而非worked