单选题为确定人体在运动时呼出气体中CO2浓度是否比安静时高，某同学进行了如下探究：作出假设：人体在运动时呼出气体中CO2的浓度比安静时高；实验过程：①在3个烧杯中，分别加入100mL蒸馏水，测定其pH。②实验者在安静状态(静坐2min)、中度运动(步行2min)以及剧烈运动(跳绳2min)后，立即分别向上述3个烧杯的水中吹入等量气体，测定pH。经多次重复实验，所得平均数据如下表： 运动状态 安静 中度运动 剧烈运动 实验前pH 6.1 6.1 6.1 实验后pH 5.9 5.6 5.3 下列有关本实验的表述不完整的是( )。A．作出假设的依据：人体运动时耗能增加，呼吸作用加强，呼出的CO2浓度增加B．实验原理：CO2在水中溶解后形成碳酸，使水的pH下降C．实验结果：运动强度越大，pH下降幅度越大D．实验结论：随着运动强度的增加，呼出的气体中CO2浓度增加，假设成寺

单选题关于教育发展与社会之间的关系，下列说法正确的是______。

单选题具有促进铁吸收功能的是( )。

单选题儿童计算能力发展的关键期是( )。

单选题This book is ______ more difficult for the students in Grade One.

单选题( )最早从幼儿心理发展和学习特点的角度论述儿童教育。

单选题2015年，网友提出的“中国式过马路”，即“凑够一撮人就可以走了，和红绿灯无关”，于戏谑中表达对目前我国交通秩序和交通文明现状的自嘲与质疑。提升围民交通文明素养应( )。 ①发挥教育在传播文明中的作用 ②优先提高公民的科学文化修养 ③开展多种形式的精神文明创建活动 ④用社会主义荣辱观引领文明风尚

单选题柳公权的代表作品是______

单选题依据我国教育行政诉讼和复议的相关规定，下列说法不正确的是

单选题关于信息技术课程目标，下列描述不正确的是( )A．增强学生的信息意识，了解信息技术的发展变化及其对工作和社会的影响B．了解计算机基本工作原理，能熟练使用各种工具和软件C．学会应用多媒体工具、相关设备和技术资源来支持其他课程的学习，能够与他人协作或独立解决与课程相关的问题，完成各种任务D．在他人帮助下识别信息来源的真实性、准确性和相关性

单选题When I was seven years old my morn was diagnosed(诊断) with cancer. The doctors told us my morn might be saved with surgery(手术). But it could also kill her. She chose to have it. The day before the surgery I was off school, and my mom planned the best day of my life, everything I loved at seven and everything that would put a smile on my lace. The day began with her waking me up saying, "Kate, I have a surprise for you. Come and see." The surprise was a doll I had wanted for the longest time. Throughout the day, she told my everything that she thought I would need to know to grow up and be a good person; she told me to be the best I could be and that I would always make her proud. We had a picnic in the park, and it was so cold that we moved to the car. The day was filled with laughter. For the first time in a long time I could see she was really happy. I would never forget her smile, or the way her eyes shone as if we were the same age. It was the best day of my life, and I will never forget the conversations we shared. My mother managed to live through the surgery. Now when I look back, I realize that the best day of my life could be her last and this could be the last day I would remember with her, the last one we shared. I also understand how unselfish a mother is.

单选题“知之者莫如好之者，好之者莫如乐之者”，这句话体现的课程理念是______。

单选题下列句子中画线词语解释有误的一项是______。

单选题在实验室中收集气体的装置有三种(如图所示)，其中适宜于用装置②收集的气体是______。

单选题讲课时，教师的语调要（ ）

单选题Which of the following cities is NOT located in the Northeast, U.S.? A. Huston B. Boston C. Baltimore D. Philadelphia

单选题我国《基础教育课程改革纲要(试行)》规定了综合实践活动的内容，主要包括四个领域是（ ）。

单选题对中小学生身份的表述是：中小学生是在国家法律认可的各级各类中等或初等学校或教育机构中接受教育的______。

单选题【2015．辽宁鞍山】应试教育重视( )。

单选题据报道，近来发现了一种新的星际分子氰基辛炔，其结构式为： HC≡C—C≡C—C≡C—C≡C—C≡N。对该物质判断正确的是______。