【单选题】函数 在原点(0,0)间断的原因是函数()
D.
在原点极限存在,但极限值不等于原点处的函数值
【单选题】(单选)在设计和选择换热器时,是否需要设计者选择管程流速:
【简答题】材料: 研究植物的光合作用是否需要CO2 呈现实验方案:将两株大小相同的天竺葵放在暗处2~3天后。分别放置在2个相同规格的密闭容器中,其中一容器装氢氧化钠溶液,另一个容器中装等量水。放阳光下照射几小时后,分别取下叶片,放入盛有酒精的烧杯里,水浴加热,溶去叶绿素,滴碘酒,观察叶片颜色。 呈现实验结果:甲中的叶片未变成蓝色;乙中的叶片变成了蓝色。 问题:本实验可以得出什么结论? 生1:乙中植物进行着光...
【简答题】完形填空 Anna lived on the side of a valley. One summer, there was a very big 1 , an d a lot of houses down below Anna's were washed away. Anna's house was 2 enough to escape the flood, so when the water ...
【判断题】若函数 在原点无极限,则函数 在原点一定不连续
【简答题】证明:函数 在原点处的两个偏导数都不存在,但函数在原点有极大值
【判断题】“势”反应的不是变化的趋势,变化的方向,而是静止的状态。()
【单选题】With real estate (房地产)______ in economy, a lot of rich farmland had to ______ new houses and offices in the area.
A.
leading the way; make way for
B.
led the way; made the way
C.
to lead the way; be made the way for
D.
leading way; be made the way for
【简答题】阅读下面材料,根据要求完成。 Anna lived on the side of a valley in Australia. Although she was poor, she was always helpful. One winter, there was a very big flood, and a lot of houses were washed away. Anna’s hous...
【判断题】“势”反应的是静止的状态,而不是变化的趋势和方向。