这是因为后面Andy and Ruby were the first to reach the top of Mount Tai的谓语是系动词were...,而不是行为动词reach.伴随状语就是要说明一个动作来的,所以这个谓语要用行为动词。原句其实是:
Andy and Ruby were the first to reach the top of Mount Tai,( and they were) tired and short of breath.
其它有关伴随状况的请到这里http://zhidao.baidu.com/link?url=320_x5irMhtdSSCyh-p08hRu7YwSHSlW-QzxGxFQ9BzyUpXfSManm_pW_N-NydYEfc97wX1CTjvBr1pIJV1Ovq参考学习
