Questions & Answers about Mittasitko tämän uuden pöydän leveyden?
Why does leveyden end in -n instead of being in the partitive?
Leveyden is the total object of the sentence. Because you are asking if the person measured the entire width (a completed action), the object takes the genitive-like accusative ending -n. If the action was ongoing, like 'Are you measuring the width right now?', you would use the partitive: Mittaatko leveyttä?
What is the dictionary form of leveyden (width), and how does the word change here?
The dictionary form is leveys. In Finnish, abstract nouns ending in -us or -ys form their stem by replacing the -s with -de- before adding an ending. So, leveys becomes the stem leveyde-, to which we add the -n ending.
Mittasitko comes from the verb mitata. Where does the -si- come from?
Mitata is a Type 4 verb. When forming the past tense of most Type 4 verbs, you use the past tense marker -si-. So the present tense mittaat (you measure) becomes the past tense mittasit (you measured). The -ko at the end makes it a yes/no question.
Why do the words tämä and uusi become tämän uuden in this sentence?