**Rule: Understanding Idiomatic Expressions.** The idiom 'throw good money after bad' means to incur further losses in a hopeless attempt to recoup a previous loss. Investing more in a 'failing project' is a classic example of this futile effort. Option (b) is the correct definition. Option (a) is the opposite. Option (c) is a different use of money. Option (d) is a literal interpretation.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a tower of strength' (similar to 'a pillar of strength') refers to a person who is extremely strong and supportive during difficult times. The word 'tower' is a metaphor for this reliability and strength. Option (c) is the correct definition. Option (a) is a literal interpretation. Option (b) is the opposite. Option (d) is a literal meaning of 'tower'.

**Rule: Understanding Idiomatic Expressions.** The idiom 'toe the line' means to accept and adhere to the rules or authority of a particular group. A teacher would demand this of students to maintain order, with punishment as a consequence for non-conformity. Option (b) is the correct definition. Option (a) is the literal origin (from athletics or military drills). Option (c) is the opposite. Option (d) is an unrelated action.

**Rule: Understanding Idiomatic Expressions.** The idiom 'under a cloud' means to be suspected of wrongdoing or to be in a state of disfavor. When money goes missing, those present are often under suspicion. Option (b) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (c) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'have it both ways' refers to benefiting from two incompatible situations. The sentence uses the negative ('can't have it both ways') to state that a choice must be made between two conflicting paths: hard work and relaxation. Option (a) is the correct definition of the idiom. Option (b) is a literal misinterpretation. Option (c) is a different quality. Option (d) is a possible outcome, but not the meaning of the idiom.

**Rule: Understanding Idiomatic Expressions.** The idiom 'on the warpath' means to be in a very angry state and actively seeking to argue or fight. A cancelled flight is a common trigger for such anger and frustration. Option (b) is the correct definition. Option (a) is the literal origin. Option (c) is the opposite. Option (d) is a literal misinterpretation.

**Rule: Understanding Idiomatic Expressions.** The idiom 'by a landslide' is used to describe a victory in an election or competition that is won by a very large margin. It creates a powerful image of an overwhelming win. Option (b) is the correct definition. Option (a) and (d) are the opposite. Option (c) is a literal interpretation of 'landslide'.

**Rule: Understanding Idiomatic Expressions.** The idiom 'burn the midnight oil' means to stay up very late working or studying. It originates from a time before electricity when oil lamps were used. Having to finish an essay 'by morning' necessitates working through the night. Option (a) is the correct definition. Option (b) is a literal misinterpretation. Option (c) is the opposite. Option (d) is related but not the meaning.

**Rule: Understanding Idiomatic Expressions.** The idiom 'walk on eggshells' means to be extremely cautious in one's words and actions to avoid causing offense or trouble in a tense situation. The announcement of layoffs would create a very tense atmosphere in a workplace. Option (a) is the correct definition. Option (b) is a literal interpretation. Option (c) is the opposite. Option (d) is a possible but different reaction.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a straight shooter' refers to a person who is frank, honest, and straightforward in their dealings with others. The fact that he 'will always tell you the truth' is a direct explanation of this quality. Option (b) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (c) is the opposite.