Question 19: The phrase "according to" fits best here as it introduces an idea from a source or authority.
Correct answer: B. according to

Question 20: The correct phrase should be "are introduced to" because it refers to the people we meet or are introduced to.
Correct answer: A. are introduced to

Question 21: "His own" is the correct form, referring to an individual's own needs, fears, and hopes.
Correct answer: D. his own

Question 22: The phrase "ought" fits here as it suggests something that is advisable or necessary.
Correct answer: D. ought

Question 23: The correct phrase is "depends on," which means the success in life is determined by how we get along with others.
Correct answer: C. depends on

Question 24: "Much" fits best here to emphasize the importance of interpersonal relations.
Correct answer: A. much