()不是轻型井点。 A.一般轻型井点 B.深井泵 C.电渗井点 D.喷射井点 发布时间:2018-08-07 13:38 │ 来源:www.tikuol.com 题型:单项选择题 问题: ()不是轻型井点。A.一般轻型井点B.深井泵C.电渗井点D.喷射井点
题型:单项选择题 An adult giraffe’s head is about six feet above its heart. This means that to (67) enough blood up to the brain the circulatory (68) must be p enough to keep the blood at very high pressure. Biologists have known for some time that giraffes solve this problem by having (69) high blood pressure, about (70) that of human beings. But an international team of biologists began to (71) about this. If giraffes have such high blood pressure, they should have a (72) problem with swelling in their legs and feet. Why don’t giraffes have swollen feet Giraffes should have (73) problem, too. Every time they bend heads (74) to drink, the blood should (75) to their heads and have a hard time (76) back up (when the head is down) to the heart. How come giraffes don’t black out when they drink The answer to the (77) feet problem, the researchers found, is that giraffes have (78) the researchers call a "natural anti-gravity suit". It (79) out that the skin and other (80) in their legs and feet are (81) stiffer and tougher than those of other (82) . As a result, the blood vessels in the leg cannot swell. Therefore, the blood has nowhere to go but back to the heart. What about blood rushing to the head (83) the giraffe bends down to drink The researchers found that the giraffe’s jugular vein, which (84) blood from the head back to the heart, has lots of one-way valves in it. In the giraffe’s neck, there are lots of muscles that flex and relax repeatedly as the animal moves its head and sucks (85) drinking water. By squeezing the valved jugular vein, they (86) blood moving back to the heart even while the animal is drinking.A.whatB.whereC.thatD.those 查看答案
题型:单项选择题 关于下列四幅图的说法正确的是____(选对一个给3分,选对两个给4分,选对3个给6分。每选错一个扣3分,最低得分为0分) A.甲图中A处能观察到大量的闪光点,B处能看到较多的闪光点,C处观察不到闪光点B.乙图中用弧光灯照射原来就带电的锌板时,发现验电器的张角变大,说明锌板原来带正电C.丙图中处于基态的氢原子能吸收能量为10.4eV的光子而发生跃迁D.丙图中处于基态的氢原子能吸收动能为10.4eV的电子的能量而发生跃迁E.丁图中1为α射线,它的电离作用很强,可消除静电 查看答案
题型:单项选择题 患者女性,46岁,因阵发性高血压,尿VMT(尿3-甲氧基4-羟苦杏仁酸)升高、CT示右肾上腺占位,诊断为嗜咯细胞瘤,准备行肾上腺肿瘤切除术,术前准备降血压最常用的药物是()A.酚妥拉明B.苯苄胺C.硝普钠D.硝酸甘油E.双氢克尿噻 查看答案