Questions

Distributed systems work in a network. They can share the network resources, communicate with each other.

Dull means not sharp, not shining, not bright, ...

Hence, the given words are all that means the opposite of dull.

There are approximately 6 trillion miles in a light-year, so the distance we need to go is 6 trillion miles / light-year times. 4 light-years is equal to 24 trillion miles. So, this whole would take 1.2 billion hours. There are 24 hours a day and 365.25 days per year, so this time in years is 137 thousand years.

'Although rain was drenching the players the players still finished the game' is the correct sentence in which an adverb clause is underlined. This adverb clause starts with a subordinating conjunction 'although' and contains a subject 'rain' and the verb is 'was drenching'. The adverb clause changes the verb 'finished' in the main clause.

Neurons are the functional units of the nervous system in the body.