因为青少年的坚持性、恒心还处在很不成熟的阶段，做事仍能够以虎头蛇尾，见异思迁，所以青少年（    ）​

完形填空。
    Hello. I'm Jenny. I have a best friend.   1 name is Amy. We are in the same school. We both can sing and dance well. She is as  2 as me.
    At school, my teachers all can make 3   happy. But we must4  white blouse with the long sleeves. I am good 5   maths and English. She 6  English. She thinks it's difficult. Yesterday we7   a party at school. We enjoyed ourselves.
    At spare time, my favourite8   is winter. I like 9  snowmen in winter. But she likes eating ice creams in summer. What a pity!
    In two months' time, we are going to go to middle school. We are very busy every day. We  10   harder than now.

关于我国地理差异的叙述正确的是（　　）

下图中横坐标为加入反应物的物质的量，纵坐标为产生沉淀的物质的量。下列反应对应的曲线错误的是