“Yojijukugo” or four-character kanji expressions, usually derived from classical Chinese texts, play an extremely important role in material for the Kanji Kentei test in general and its level 1 in particular: knowledge of Yojijukugo is required not only in part 4 (where they are explicitly given for questions), but other parts of the test as well where vocabulary based on Yojijukugo can be featured as part of problems for reading, writing, proverbs, antonyms-synonyms.
Here I will introduce ten different Yojijukugo which meaning I found particularly interesting.