20℃时，在三个各盛有100g水的容器中分别加入甲、乙、丙三种纯净物（不含结晶水，不与水反应）各10g，充分溶解后，情况如下表所示 ，下列有关说法不正确的是（   ）

    Daniel comes from Sydney. He is now staying in Beijing with his family. He usually gets up at about 6:30 am and has breakfast at 7:00 am. Then he leaves home at 7:15 am.

    He gets to school at 7:45 am. His first class begins at 8:00 am. There are four lessons in the morning. Morning classes are over at 11:50 am, and he has lunch 10 minutes later.

    Afternoon classes begin at 1:30 pm. There are two lessons in the afternoon. They are over at 3:10 pm. Daniel usually stays at school for another hour to play soccer, and then goes home.

①维护自己的合法权益时缺少了重要的证据

②不能了解所购商品的真实情况

③售后服务时缺少了必要的凭证

④使国家的税收发生流失