宁夏回族自治区实现社会、经济可持续发展的关键在于（　　）

   Good morning! Now let me report the discussion work in our group. Wu Jun cleans up rooms  ____  weekends and Jia Mei likes cooking dinner with her mum. Wang Ping sometimes  ____ (wash) clothes for her family. As for me, I usually help my father water the flowers.
   In my opinion, it is necessary  ____  us students to do some housework by doing it, we can help our parents and understand them better. We’ll also learn to take care of  ____ . Besides, we can relax ourselves from hard work and develop our abilities.
That’s all. Thanks for  ____  ( listen)!

与前代相比，明清时期对外关系的新现象是（     ）

科举制度在我国沿用了一千三百多年，请问中国科举制度的起止朝代是（  ）