What are the three hardships the people of Copenhagen must endure because of the war in Number the Stars?

The citizens of Copenhagen must cope with a constantly lessening supply of things they need. In the first chapter, readers are told that coffee and tea have long disappeared and that women sip hot tea with herbs. Then readers learn that fuel is in short supply and that the "winter nights were terribly cold." Electricity is rationed, and they often use candles for light. This doesn't even provide enough light for Ellen's father, a teacher, to see well enough to grade his students' papers.
They must also live in fear of the soldiers who walk their streets, ready to sneer at them and terrorize them at any moment. When the girls are walking home from school one day, they are stopped by soldiers questioning how well they do in school. Soldiers don't engage in small talk, so the girls are left to wonder the real purpose of the confrontation. Later soldiers burst into their home and demand to know how two blonde sisters could have a brunette sister as well. Annemarie's father must quickly devise a plan to hide the real truth and then sell this lie to the officers. There is no room for error in dealing with the ongoing threat of these confrontations.
They must leave their homes to survive. People falling into classifications established by Hitler were actively sought out and sent to concentration camps—or killed. Many people live in terror that their lives will soon end, so they are forced to flee their homes in hope of survival. With the brave assistance of those in the Resistance, some of these people found this hope—but at great risk to all involved. Annemarie finds that the fewer details she knows about how all this happens, the better she is in dealing with soldiers' inquiries.