单选题罗杰斯的“以学生为中心”、“让学生自发学习”、“排除对学习者自身的威胁”的教学原则属于( )。

单选题The following day l ran my first race at high ______.

单选题观察细胞中染色体行为并计数时，使用光学显微镜的正确方法是( )A．低倍镜对焦，将观察目标移至视野中央，转用高倍镜并增加进光量，调焦观察B．低倍镜对焦，将观察目标移至视野中央，转用高倍镜并减少进光量，调焦观察C．低倍镜对焦，转用高倍镜，将观察目标移至视野中央，减少进光量，调焦观察D．高倍镜对焦，将观察目标移至视野中央，增加进光量，调焦观察

单选题用数字1、2组成四位数，且数字中至少出现一次1、2，则这样的四位数有______个．

单选题教师在教育工作中要做到循序渐进，这是因为______。

单选题已知a=(3，1)，b=(1，2)，则(a+2b)(2a—b)=( )．

单选题下列关于神经肌肉(肌肉指骨骼肌)接点及其相关结构和功能的叙述，正确的是( )。 A．一个骨骼肌细胞中只有一个细胞核 B．神经肌肉接点的突触间隙中有组织液 C．突触后膜的表面积与突触前膜的相同 D．一个乙酰胆碱分子可使突触后膜产生动作电位

单选题定义在R上的函数f(x)满足f(x+6)=f(x)，当-3≤x＜-1时，f(x)=-(x+2)2，当-1≤x＜3时，f(x)=x，则f(1)+f(2)+f(3)+…f(2012)=______ A.335 B.338 C.1678 D.2012

单选题社会主义经济制度的物质技术基础是______。

单选题设a，b是两个非零向量，下列说法正确的是______ A.若|a+b|=|a|-|b|，则a⊥b B.若a⊥b，则|a+b|=|a|-|b| C.若|a+b|=|a|-|b|，则存在实数λ，使得a=λb D.若存在实数λ，使得a=λb，则|a+b|=|a|-|b|

单选题A lot of facts still have to be ______ before we can make a final decision about who should be held responsible for the accident.

单选题用Photoshop处理照片时，为了以后能够接着处理，保留图片信息时需保存为______。

单选题Don't be too ______ about things you are not supposed to know. A. strange B. amusing C. curious D. conscious

单选题D When a young man was 16,his father seriously said to him,"I' ll give you whatever you want before you are 18. But after that, I won' t care much about you. " When his 18th birthday was coming, the young man began thinking about looking for a job. So he sent his resumes (简历)to many companies he liked on the Internet. "However, most got no replies," he said. "Maybe they were surprised about my primary school education. " By chance ,one of his friends was looking for someone ,who could work as an egg porter(搬运工) in the supermarket, for half a dollar a box. Facing lots of difficulties in getting a job, he said,"I'll take this job. At least I can make some money for my gas. "Then every day,he drove his car, his 18th birthday gift,to work in the supermarket. He did that for three months. Later he heard that a newspaper was looking for a network technician (网络技术员), so heasked for it. But they were also worried about his school education. He practiced his skill right infront of the computer , and showed the managers the web pages he had made. He started to work the next day, and became the leader of the network department(部门)in less than a year. And now, the 23-year-old man is a boss. Last year, he started a magazine for children, with himself as the editor in chief(主编). And the only writer was his father.

单选题《富春山居图》是元代“元四家”之首______的晚年力作，所表达的意境疏朗清新、开阔俊秀；清代时期作品断为两段，现由浙江省博物馆和台北故宫博物院各收藏一段。2011年6月初，两段作品在台北合璧隆重展出，引得万众瞩目。

单选题网络中计算机之间的通信是通过协议实现的，它们是通信双方必须遵守的约定。Internet主要采用的协议是( )A．FTPB．HTTPC．IPX/SPXD．TCP/IP

单选题教学过程中，孙老师有明确的教学目标，丰富的教学内容，合理的教学方法。该教师的教学监控能力属于______。

单选题( )是品德形成的基础。

单选题—Let"s go and see Mr. Brown. —I"m afraid this isn"t a very ______ moment to see him, as he"s quite busy these days.

单选题Today we have chat rooms, text messaging, emailing...but we seem ______ the art of communicating face-to-face.