Which one is grammatically correct?

i had a much better understanding of how they work.
i had a much better understanding of how they worked.

Which words best describes the speakers?

Read the passage. (1) the first skateboard was constructed of old roller-skate wheels attached to a piece of wood. (2) improvements were made to the skateboard in 1959. (3) the year that the first commercially made skateboard appeared. (4) soon after, skateboarding began to grow in popularity. (5) in 1963, skateboard manufacturers formed the first professional skateboarding team. (6) that same year, the first organized skateboard competition took place, in california. which is the most effective way to correct the fragment in sentence 3? attach the fragment to sentence 4. attach the fragment to sentence 2. insert the phrase in the united states to the end of the fragment. insert the verb had before the verb appeared.

Each pair of sentences can be combined to create one compound sentence. determine which choice best combines them. refinishing furniture is a creative hobby. not everyone loves to scour garage sales to find old items. going to flea markets can you to notice unique qualities in used items. beauty can be found where you least expect it. specialized equipment can make the refinishing process easier. painting the furniture can be creative with the right tools. some people like refinishing old furniture. others prefer buying new items.