Answer:
serious
Explanation:
it sounds formal and has no expression; it is serious
I'm assuming that the underlined word is answer and i think its transitive. but i'm not completely sure.
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)
A) the idea that he is under a lot of stress because he wants something he can’t get
