科举制度是一种（    ）

在探究“压力的作用效果与哪些因素有关”的实验中，小明和小华利用所提供的器材（小桌、海棉、砝码、木板）设计了图（a）、（b）两个实验，通过观察图（a）、（b）后得出“压力一定时，受力面积越小，压力的作用效果越明显”的结论．此后小华把小桌挪放到一块木板上，发现小桌对木板的压力效果不够明显，如图（c）所示．通过对图（a）、（c）的比较又得出“压力一定时，受力面积越小，压力的作用效果越不明显”的结论．

请你根据已学过的压强知识分析：

对清朝前期实行的闭关锁国政策的准确理解是（    ）

2016年8月上半月，酷暑使蛋鸡处于歇伏期，产蛋率明显下降，且高温下鸡蛋不易保存，市场供应量趋少，下半月随着学校开学和中秋节临近，鸡蛋集中各货需求增加，鸡蛋价格开始土涨。鸡蛋价格变化（    ）

①是由供不应求导致价格上涨的    ②表明价值的变化决定价格变化

③是多种因素影响供求关系所致    ④会使人们对鸡蛋需求急剧减少

阅读短文, 根据首字母提示补全单词。

    There is a p____near our school. We can see many trees and flowers there. Some flowers are red, and some are y____. We can see a hill behind the park, too. At the foot of the hill we can see a r____. There are some boats on it. Children like to go there. It is Monday today. There are many young pioneers(少先队员)in the park. Some are walking and singing. S____are dancing and p____ games. Ann and h____ sister Kate are flying a k____. Tom and his brother Sam are t____a frisbee (飞盘). Their lather and mother are sitting u____ a tree. All the people are h____a good time.