What does an adverb modify?

What is the adjective in the sentence: The straight ribbon of freeway, led across the vast expanse of desert."?

What is the function of the underlined word in the sentence: "The shovel bit deep into the black soil."?

The flagman motioned the car right.

The building jutted high into the sky.

I left at six for an early appointment.

How is the word hard used in the sentence: "I solved the hard algebra problem quite easily."?

Identify the underlined clause as adjective clause or adverb clause: The people whom I invited to my study group are bringing snacks.

As much as I love painting, I have other things to do.