"Whan that Aprill with his shoures soote / The droghte of March hath perced to the roote"
In this line, "Whan" (when) is the subject, "hath perced" (has pierced) is the verb, and "the droghte of March" (the drought of March) is the object.
However, there are some instances where Chaucer deviates from this word order for poetic effect or to create a certain rhythm or emphasis. For example:
"A knyght ther was, and that a worthy man"
In this line, the object "a worthy man" comes before the verb "was" for emphasis.
Overall, the word order in the General Prologue generally follows the subject-verb-object pattern, but there are some exceptions for artistic purposes.