Pahlsson and her husband searched the kitchen, checking every corner, but turned up nothing.
本句中,searched the kitchen, checking every corner, turned up不是三个并列谓语动词吗,为什么是checking(分词形式)?
本句中,searched 和 turned up 是并列谓语动词;checking every corner 是现在分词短语,作searched the kitchen 的伴随状语。