dave went through his pockes looking for the keys.为什么不是to lo

1。这个句子中并没有两个“谓语动词”,只有一个：went。looking是“非谓语动词”。2。非谓语动词有三种形式：不定式,-ing 动词和过去分词。他们在句子中不充当谓语,所以称“非谓语动词”。3。以本句为例,句子有了谓语动词went,那么后面只能用非谓语动词了。-ing形式和不定式都可以用,但是意思和结构不一样的。a。looking 是现在分词,做状语,表示伴随状况,即：手伸进口袋的同时在寻找。b。to look动词不定式,做状语,表示目的。即：手伸进口袋的目的是为了寻找。4。但如果句子改一下,变成两个句子,就可以用谓语动词形式了。dave went through his pockes and he was looking for the keys。或者As dave went through his pockes he was looking for the keys。请注意谓语动词和非谓语动词的不同形式。