"We drink our tea with sugar."

Translation: Wir trinken unseren Tee mit Zucker.

[Cristti]

Why isn't it Unsere Tee ?

[gabrielzech]

Because "Tee" is masculine, and as it is under accusative, you should add -en to "unser"

[seamusrowan]

Am I correct to think that "mit Zucker" is dative? I'm trying so hard to get a grasp on these cases. It's making me crazy.

[drakferion]

Yes. Mit goes with the indirect object, and is always dative.
«"Mit das" gibt es nicht», as I am always told. ;-)

[EugenNagy]

Why cant I say: Wir trinken unseren Tee mit dem Zucker? Aus, bei, mit, nach, von, zu is connected with Dativ (der, des, Dativ - dem, den). Is it then like with that sugar?

[Daniel993688]

"dem" is unnecessary.