3.---Really nice ----C---you.I'm going to miss you.---Don't

3.---Really nice ____C___you.I'm going to miss you.---Don't forget to give me a ring,will you?3.---Really nice ___C____you.I'm going to miss you.---Don't forget to give me a ring,will you?A.knows B.to know C.to have known D.knew为什么不用过去范围内的时态而用完成时