Adverbs refer to the words which modify an adjective, a verb or an adverb. Adverbs further answers to the following question of,
<em>How? Where? When? and Why?</em>
Therefore, in the sentence, <em>yesterday Rachel worked slowly because she was so tired.</em>
Words which function as an adverb are- yesterday, so and slowly.
Yesterday answers from the following questions of<em> when?</em>
So acts as a modifier to an adverb <em>slowly</em>, and
Slowly modifies an adjective <em>slow</em>.
True they also have done electrical gadgets,nanotechnology
<span>Rochester’s vision has been restored in one eye.</span>
The groomer had to get 3 big red ribbons out of the dog's matted fur
maybe the author just want to keep that info secret and the story maybe not true at all so author doesn't want to tell readers, that what I think!