The American Dream is the belief that anyone, regardless of where they were born or what class they were born into, can attain their own version of success in a society where upward mobility is possible for everyone. The American Dream is achieved through sacrifice, risk-taking, and hard work, rather than by chance.
In English, commas should be used within a quote, in order to separate it from the indirect speech, and before the quote, for the same reason.
Thus, this is the correct answer:
"I know you did it," the detective accused the murderer, "and I can prove it!"
"Please remember to watch the gap," the conductor warned.
Take, for instance, the world of science. Scientists have to get or obtain, then organise, analyse, record and interpret all the data they have collected. On that basis, the world is enriched culturally and scientifically with reliable and mostly accurate research on our lives, our history, our role in the Universe.
Then, go back to revisit our history, starting with Galileo or Da Vinci who was a painter, an engineer and an inventor of his own time. Painters , for instance, throughout the human history, have communicated states of mind through symbols or simply innovated Art by their unthoughtful means of communication: brushes.
