Ulrich'sfriendAnnawasmissingatschool．Hismothersaidthatperhapsshehadgoneintohiding．Thatwasthehopeanyway-thatthefamilyhadleftontheirownandhadnotbeensentononeoftheprisontrainstoGermanyorPoland．Somanypeopl

　　Ulrich's friend Anna was missing at school．His mother said that perhaps she had gone into hiding．That was the hope anyway-that the family had left on their own and had not been sent on one of the prison trains to Germany or Poland．So many people in his city had disappeared since the Nazis came to Amsterdam in 1940．The streets，once crowded with busy shoppers，were now filled with tanks and soldiers．

　　No one felt safe，except maybe the collaborators（通敌者）．Who were they？Who would betray their friends and let their neighbors be arrested？Ulrich remembered his friend Anna：her father had a small business right down the road from his house．Her sister，Margot，was in the upper school，where Ulrich's sister was in her class．

　　When he walked to or from school，Ulrich studied the faces of the people on the street．Some looked concerned and cast their eyes downward as they walked，trying not to be noticed．His own parents had that look，like ghosts walking and wondering what had happened to them．The ones that bothered him were those who smiled，who acted like nothing was wrong．"Were they blind？"he wondered．Worse were those who moved into the houses and took the businesses of their missing neighbors．They seemed too assured，too content．They may be Dutch，Ulrich thought，but they are the enemy，too．They were the ones who made the occupation easy．He hoped that when the war was over，the rightful owners would come back and toss them out on their ears．

　　School was not the same either．It was more than the missing students，though that was the biggest part of it．The teachers，who once seemed to know everything，were different，too．They seemed afraid to teach history，afraid that the authorities would not like what they said．They jumped when a student dropped a book．It was as if they all had to hold their breath．

　　It was nearly spring．Already tulips（郁金香）were fighting their way out of the cold ground．How many more winters，springs，summers，and falls would go by unt