小林准备进行如下操作实验；把一根长为40cm的铁丝剪成两段，并把每一段各围成一个正方形．

12月份，自东向西穿过直布罗陀海峡的航船常遇到

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．

在△ABC中，sinA：sinB：sinC= $\sqrt{3}$ ：4： $\sqrt{31}$ ，则角C的大小为（   ）

小明向他的美洲朋友介绍亚洲“世界之最”，其中错误的是（    ）