there was a pleasant smile on his face为什么smile不用过去式?

there was a pleasant smile on his face为什么smile不用过去式?
there was a pleasant smile on his face
为什么smile不用过去式?

there was a pleasant smile on his face为什么smile不用过去式?
这里smile是个名词啊,这里不是当做动词用,所以当然也就没有过去式之分了

smile可以做名词，在这里就是名词，微笑的意思