一个高考英语单选题----题不是很难,解释明白很难,
33、I had been working on math for the whole afternoon and the numbers before my eyes.
A：swam B：had swum
我想知道,and连接两个句子,谓语的时态不该是一致的吗?这个是怎么回事?and还有别的用法吗?