( )为了读数方便,测量前一般把百分表的主指针指到表盘的“零位”,当提起测量杆,再查看主指针所指零位是否变化。直到将百分表校准为止。
体现我国教学的根本方向和特点的教学原则是
A.理论联系实际的原则
B.科学性与教育性相结合的原则
C.因材施教原则
D.直观性原则
用下面语句调用库函数malloc,使单精度型指针p指向具有40个字节的动态存储空间,请填空。 p=(float*)【 】;
A.通过图示获得直观理解,并不是数学理解的最后步骤。
B.具有很强的处理抽象运算符号能力的人,不一定具有抽象的数学理解能力。
C.几何学课程中的图示方法是一种有效的教学方法。
D.培养处理抽象运算符号的能力是几何学课程的目标之一。
E.存在着一种教学方法,可以有效地用于几何学,又用于代数。
下列有关能量金字塔的说法有误的是()
A.能量金字塔是指一段时间内生态系统中各营养级所同化的能量
B.能量金字塔较直观地表明了营养级之间的依赖关系
C.能量金字塔受个体大小、组成成分和代谢速率的影响
D.能量金字塔可以较准确地说明能量传递的效率和系统的功能特点
根据气力输送的特点,降低动力消耗,节约能源是一个重要的研究课题,从经验中知,管道内径是关于能耗的重要参数。直观上看,当输送量一定时,管径过小,输送易阻滞,管径过大,虽输送畅通,但又造成能量的浪费。根据经验,把管径分成三组,各组的试验结果如下表所示,试用方差分析法比较各组的效果.
管径(mm) | 单位功耗 |
230 | 0.0308,0.0476,0.0504 |
250~260 | 0.0532,0.032,0.0218,0.028,0.028, 0.042,0.0336,0.042,0.042,0.028 |
280~320 | 0.07,0.07,0.0644,0.0312,0.0756,0.0756, 0.07,0.0588,0.0588,0.042,0.0308,0.0364, 0.0448,0.21,0.154,0.1064,0.1288,0.112, 0.1064,0.1288,0.0756,0.0644,0.0504,0.0644, 0.0504,0.0308 |