**Rule: Understanding Idiomatic Expressions.** The idiom 'an ace up one's sleeve' comes from card games and refers to a hidden advantage that is kept in reserve until the opportune moment. In a debate, this could be a powerful, unexpected argument. Option (b) is the correct definition. Option (a) is the literal origin. Option (c) is the opposite. Option (d) is a profession that uses similar tricks, but it is not the meaning of the idiom.

**Rule: Understanding Idiomatic Expressions.** The idiom 'blow a fuse' means to lose one's temper and become very angry. It is a metaphor based on an electrical fuse blowing when overloaded. A cancelled flight is a common trigger for such an outburst. Option (a) is the correct definition. Option (b) and (d) are literal misinterpretations. Option (c) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'in the firing line' means to be in a position where one is vulnerable to attack, criticism, or dismissal. A team's poor performance often puts its coach or captain in this position. Option (a) is the correct definition. Option (b) is a literal interpretation. Option (c) is the opposite. Option (d) is an incorrect interpretation of 'firing'.

**Rule: Understanding Idiomatic Expressions.** The idiom 'bounce ideas off someone' means to share one's ideas with another person to get their feedback and opinion. This is a common practice in creative collaboration, such as between comedians. Option (b) is the correct definition. Option (a) is a similar but different idiom ('throw something at the wall...'). Option (c) is the opposite. Option (d) is an incorrect interpretation of 'chemistry'.

**Rule: Understanding Idiomatic Expressions.** The idiom 'live from hand to mouth' describes a precarious existence of having only enough resources to satisfy immediate needs, with no money left for the future. Being worried about one's next meal is a hallmark of this situation. Option (b) is the correct definition. Option (a) and (d) are the opposite. Option (c) is a literal misinterpretation.

**Rule: Understanding Idiomatic Expressions.** The idiom 'a rough patch' (or 'a bad patch') refers to a period of time marked by problems or hardship. A company facing financial or operational trouble would be going through a rough patch. Option (a) is the correct definition. Option (b) and (d) are literal misinterpretations. Option (c) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'at loggerheads' means to be engaged in a dispute or conflict. Having opposing political views is a common source of such disagreement. Option (a) is the correct definition. Option (b) and (d) are the opposite. Option (c) is a literal misinterpretation.

**Rule: Understanding Idiomatic Expressions.** The idiom 'give free rein' means to grant someone full autonomy and control over something. It comes from the idea of dropping the reins to let a horse run freely. Managing a project 'as he sees fit' is the definition of having this freedom. Option (b) is the correct meaning. Option (a) is a literal interpretation. Option (c) and (d) are the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'in a class of one's own' means to be unique and superior to everyone else in a particular skill. Being 'far better than his competitors' is a direct explanation of this idiom. Option (b) is the correct definition. Option (a) and (d) are literal misinterpretations. Option (c) is the opposite.

**Rule: Understanding Idiomatic Expressions.** The idiom 'keep one's cards close to one's chest' means to be very secretive about one's plans or ideas. It comes from card games where players hide their cards from opponents. The fact that 'no one knows what his next move will be' is a result of this secrecy. Option (c) is the correct definition. Option (a) is the literal origin. Option (b) is the opposite. Option (d) is a possible but not necessary interpretation.