I pay a lot of attention to the evolution of Bud's language, not just because language acquisition has been one of his greatest challenges and not just because his language skills seem to be an indicator of his development overall, but also because, when you come right down to it, I'm just a big old grammar geek.
I've written previously about Bud's use of the phrase "What did I did?" to call our attention to something he's done. As has sometimes happened with other phrases, "What did I did?" has come to have a variety of meanings for Bud. Sometimes "What did I did?" means "Do you recognize my achievement, and will you shower me with praise?" Other times "What did I did?" means "Can you tell me the words I should use to describe the thing that I just did?" Still other times "What did I did?" means "Are you aware of this thing that I did... and am I going to be in trouble for it?"
"What did I did?" is a question in the simple past tense: it indicates that his activity has been completed. However, in recent months, as Bud's language has continued to develop, he's started playing with tenses and we've been hearing the question earlier, while the activity is still in progress: "What I'm doing?"
Fittingly, with questions like "What I'm doing?," Bud is moving his language forward by using the "present progressive" tense.
In the past week or so, he's been playing with a new tense by using the helping verb have, or, more accurately, the contraction 've, as he did on Monday when he asked me, "What you've got?" and this morning when he tried a new form of "What did I did?" and asked me "What I've did?"
As I drove to work this morning I tried to remember the name of the tense that uses "have," but I couldn't come up with it. So, this afternoon I pulled out my handy reference guide and looked it up:
What I've did? = past perfect tense
What you've got? = present perfect tense
Past perfect. Present perfect.
My hunch is that pretty soon he will have mastered it all.
And for those keeping score at home: that makes the future perfect, too.