Preposition or Adjective?

The BLUE pencil is on the table.

• preposition

• adjective

Their new class ended AROUND ten o'clock.

• preposition

• adjective

There were two happy dogs IN the pool.

• preposition

• adjective

There were two HAPPY dogs in the pool.

• preposition

• adjective

The SILLY student jumped onto the table.

• preposition

• adjective

The silly student jumped ONTO the table.

• preposition

• adjective

Don't put that heavy box of books UNDER the table.

• preposition

• adjective

Don't put that HEAVY box of books under the table.

• preposition

• adjective

There were yellow tomatoes mixed AMONG the red ones.

• preposition

• adjective

There were YELLOW tomatoes mixed in among the red ones.

• preposition

• adjective