Google you can?
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Yoda's speech patterns became more consistent as more movies came out. In essence, George Lucas became more practiced in Yodish and settled into a consistent set of rules. For example, in the third movie, Return of the Jedi, Yoda asks "Look I so old to young eyes?" which doesn't comply with standard English or "standard" Yodish. In standard English, we'd say "Do I look so old to young eyes?" and in standard Yodish we'd say "Look so old to young eyes, do I?" Presumably, there are fewer of these non-standard sentences in the later movies, although without analyzing the full scripts, I can't confirm or refute this idea.
Yoda spoke an unusual version of Basic. He usually tended to place verbs (especially auxiliaries) after the object and subject (an object-subject-verb format). An example of Yoda's speech pattern: "When nine hundred years old you reach, look as good you will not." Most agreed that this pattern of speech was convoluted, and while it seems as though others of his species (e.g. Yaddle) had the same penchant for rearranging sentences, not all of them did (e.g. Vandar Tokare).
Yoda's grammar depends on the intent of the sentence and while he follows his grammar for the most part, his operator, or script writer does make a few errors
Yoda uses four basic sentence types: imperative, interrogative and declarative and I will consider the fourth structure to be that of the standard English vernacular structure (hereafter SEV) which are often, but not always exceptions to the structure of Yodish.
Done I am