Answer:
Mr. Van Daan is caught stealing bread in the Annex. This changes our understanding of the past food shortages in the Annex, as they may have been caused by Mr. Van Daan stealing food for himself, leaving the others without food.
'Exert' means to apply force on influence over something else, this can be in a negative or positive way. In this quotation, it means that language, if used correctly, has the ability to express a 'hidden power'. It's also worth mentioning that the simile is relevant as the moon has an influence on the level of tides on Earth.
The chorus in an Ancient Greek play was extremely important because it helped the viewers to follow along. Often times it summarized what happened in a certain act/scene/play, which helped people who did not understand it to, well, understand it. It also often provided insight into characters minds. It told things about the characters that they could not tell about themselves, which could help the viewer predict what was going to happen in the upcoming scenes.