and I could feel my smile yanking the corners of my mouth up.

问题描述:

and I could feel my smile yanking the corners of my mouth up.
could feel 是can feel的过去时?
yanking是什么语法成分?现在分词短语?yanking the corners of my mouth up

could 在这里是过去时还是委婉语气,要看上下文的时间.
yanking the corners of my mouth up 是 my smile 的宾语补足语,就好比 make sb. do sth.这种样子的,当然不完全一样,但是这里是现在分词短语做宾语补足语