读如图“地球公转示意图”和“旗杆影子示意图”，完成下列问题。

选词填空。

合适    适合

①然而，要找到____移植的骨髓；又谈何容易。

②只要发现哪块搭石不平稳，赶路的人一定会找来____的石头搭上。

开放    放开

③少年儿童就像阳光下____的花朵。

④只要不____手中木板，就不会沉下去。

连接    接连

⑤他____翻了十几个跟斗，站起来时脸不红，心不跳。

⑥这座大桥是____两个城市的重要通道。

1990年12 月邓小平在同几位中央领导同志谈话时指出：“社会主义不是少数人富起来，大多数人穷，不是那个样子，社会主义最大的优越性就是共同富裕。”材料中邓小平主要阐述了

选词填空。

excited, skill, may, they, without, but, include, part

    American teenagers(青少年)enjoy doing part-time jobs．They think it's an important____of growing up．They can learn some important____by doing part-time jobs and they can also make some money in this way．
    American teenagers usually begin to do part-time jobs at the age of 14．On weekdays，they____go to work a few hours a week after school．They usually work for longer at weekends．
    In summer,American teenagers are____if they find part—time jobs at camps or swimming pools．These jobs can bring____much fun．
    Some difficult jobs____teaching， nursing and police work．____these jobs can be helpful for their future．When they grow up，the students with work experience are more likely (可能的)to be successful than those____work experience．

下列关于人体细胞结构和功能的叙述，错误的是 (　　)