单选题下列各项中表达正确的是______A．Si的原子结构示意图：B．聚乙烯的结构简式：C．NH3的电子式：D．HCl的电子式：

单选题在新一轮基础教育课程改革中，各学科的纲领性指导文件是______。 A.教学计划 B.教材 C.课程标准 D.学科计划

单选题下列捕述中不正确的是______。

单选题六代乐舞中黄帝时期的乐舞是______。

单选题我国《中小学教师专业标准(试行)》的基本理念是学生为本、______、能力为重、终身学习。

单选题下列鲁迅作品中（）不是杂文集。

单选题古希腊学者阿基米德在浴缸洗澡时突然发现浮力定律，解决了“王冠之谜”。这种思维是______。

单选题上课的先决条件是______。

单选题瞬时记忆又被称作( )。A．知觉记忆B．工作记忆C．感觉记忆D．声像记忆

单选题桑代克提出的学习三定律指的是______

单选题在教学活动中，教师不能满足于“授人以鱼”，更要做到“授人以渔”。这说明教学中应该重视______。

单选题归因总是与______联系在一起的。

单选题一切从实际出发，是我们制定路线、方针的基本原则。现阶段中国最大的实际是______。

单选题Different creatures have developed some pretty creative ways to get their rest and stay safe. The lizard likes to sleep at the far end of small branches hanging out over a pond or lake in the rain forest. If a snake tries to slither up the branch to eat it, it will shake the branch and knock the lizard off, and the lizard will fall safely into the water. Chameleons can change color to match their surroundings in order to hide even while sleeping. Gorillas like to sleep high in the trees. They build a new bed every night, sometimes taking up to hall an hour to pile branches, twigs, and leaves into a comfortable bed. Birds also find it safe to sleep in the trees, but unless they have eggs or young chicks, they don"t use a nest. They just lock their feet around a branch and hang on. A special tendon in their legs is automatically tight when they are at rest, so they won"t let go and fall. Dolphins live underwater, but must come to the surface to breathe. Scientists now believe that dolphins may sleep with only half their brain, while the other hall stays awake to keep them safe and breathing. Seals also do this, lying on their sides on the surface of the water with one flipper underwater paddling to keep their noses above the surface. Some ducks may also have this ability, and actually sleep with one eye closed and one eye open.

单选题如图，扇形纸扇完全打开后，外侧两竹条AB、AC夹角为120°．AB的长为30cm，贴纸部分BD的长为20cm，则贴纸部分的面积为（）．

单选题【2014．广西】班主任对学生进行操行评定时应慎用的评定等级是( )。

单选题清代三大木版年画产地是天津杨柳青、( )、山东潍县杨家埠。

单选题已知向量c=(2，3，-1)-2(-1，0，2)，若用标准基i、j、k表示c，则c=______．

单选题______是教育活动应遵循的根本指导原则。