Learn German: Das Restaurant ist sehr teuer. - The restaurant is very expensive.

Restaurant is a neuter noun. While noun genders usually need to be memorized, a helpful tip is that many foreign words borrowed from other languages are neuter in German. Other common examples include das Hotel and das Café.

Why doesn't the adjective teuer have an ending to match the neuter noun das Restaurant?

In German, adjectives only take a special ending when they come directly before the noun they describe. Because teuer comes after the verb ist, it acts as a predicate adjective and stays in its basic dictionary form without any extra endings.

Could I use viel instead of sehr to say the restaurant is very expensive?

No, you must use sehr (very) when you are boosting a descriptive adjective like teuer. You use viel (much or a lot) when talking about amounts of things or with verbs, such as Ich esse viel (I eat a lot).

How would I change this sentence to use the current lesson's phrase, es gibt?

If you wanted to say 'There is a very expensive restaurant', you would use es gibt followed by the accusative case: Es gibt ein sehr teures Restaurant. Our current sentence just describes a specific restaurant as a simple fact, so it uses ist and stays in the nominative case.