Final answer:
The corrected sentence should use a comma instead of a semicolon: 'William Shakespeare was in a terrible mood last Tuesday. His best friend, nevertheless, was able to cheer him up by doing a silly dance.'
Step-by-step explanation:
The correct punctuation and capitalization for the provided sentence should be:
William Shakespeare was in a terrible mood last Tuesday. His best friend, nevertheless, was able to cheer him up by doing a silly dance.
The semicolon used initially should be replaced with a comma as it introduces a contrasting clause that is related to the main sentence. The proper use of punctuation, such as commas, semicolons, and periods, are critical to convey the desired meaning clearly and precisely. This is especially important when trying to emulate the poetic language and dramatic tension found in the works of playwrights during the 16th and 17th centuries, like William Shakespeare and Christopher Marlow.