Answer: "Enhance his standing" means to improve one's reputation, status, or position, often in a particular context. In this context, the phrase might refer to someone taking actions that are likely to improve their position or reputation in a specific group or community.
For example, if a politician takes a stance on an issue that is popular with a particular constituency, they might be said to be enhancing their standing with that group. Similarly, if an athlete performs exceptionally well in a championship game, they might enhance their standing within their sport and among fans.
The phrase "enhance his standing" often implies that the individual is actively taking steps to improve their position or reputation, rather than simply waiting for it to happen naturally. It may also suggest that the individual is strategic in their actions, and is seeking to improve their standing for a specific purpose.
Explanation: The phrase "enhance his standing" means to improve or increase one's reputation, status, or influence in a particular context or group. In the given context, it refers to Matsuoka's reputation or standing in Washington, D.C., the capital of the United States. The statement suggests that Matsuoka's insulting language and speculation on his own sanity during the meeting with Ambassador Grew were not likely to improve his reputation or standing in Washington, but rather damage it.