Organizing an outline would be your answer.
Answer:
Since the middle of the 20th century, scientists <u>have found</u> cures for many diseases. However, so far no one <u>has discovered</u>
Explanation:
those are the perfect tenses for (find) and (discover)
How does a soliloquy differ from an aside? ... During a soliloquy, only the character making the speech is present onstage, while during an aside, others characters may be present onstage. A soliloquy is the opening scene of a play, while an aside is the closing scene of the play
